<PAGE>   1

      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 1, 1998
                           REGISTRATION NO. 333-_____
 ------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                       ----------------------------------

                                    FORM S-8
                  REGISTRATION UNDER THE SECURITIES ACT OF 1933
                       ----------------------------------

                         UNITED SECURITY BANCORPORATION
             (Exact name of registrant as specified in its charter)

<TABLE>
<S>                                                  <C>       
           WASHINGTON                                       91-1259511
  (State or other jurisdiction               (I.R.S. Employer Identification Number)
of incorporation or organization)
</TABLE>

           9506 NORTH NEWPORT HIGHWAY, SPOKANE, WASHINGTON 99218-1200
            (Address of Principal Executive Offices)      (Zip Code)

         UNITED SECURITY BANCORPORATION 1995 INCENTIVE STOCK OPTION PLAN
                              (Full title of plan)

                  Please send copies of all communications to:

<TABLE>
<S>                                              <C>
RICHARD C. EMERY                                 STEPHEN M. KLEIN
United Security Bancorporation                   Graham & Dunn, P.C.
9506 North Newport Highway                       1420 Fifth Avenue, 33rd Floor
Spokane, WA  98218-1200                          Seattle, WA  98101
(509) 467-6949                                   (206) 624-8300
</TABLE>

                         CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
 -------------------------------------------------------------------------------------------
                                                              Proposed
                                         Proposed maximum     maximum
Title of              Amount             offering             aggregate         Amount of
securities to be      to be              price                offering          registration
registered            registered         per share (1)        price (1)         fee
----------            -----------        -------------        ---------         ---

<S>                   <C>                <C>                  <C>               <C>      
Common shares,        300,000 (2)        $21.50               $6,450,000        $1,902.75
no par value
--------------------------------------------------------------------------------------------
</TABLE>

Notes:
    1.  Estimated solely for the purpose of calculating the amount of the
        registration fee. Pursuant to Rule 457(c) under the Securities Act of
        1933, as amended ("Securities Act"), the price per share is estimated to
        be $21.50 based upon the average of the high ($21.50) and the low
        ($21.50) trading prices of the common stock, no par value per share
        ("Common Stock") of United Security Bancorporation (the "Registrant") as
        reported on the Nasdaq Stock Market on June 30, 1998.
    2.  Shares of Registrant's Common Stock issuable upon exercise of option
        outstanding under the United Security Bancorporation 1995 Incentive
        Stock Option Plan (the "Plan"), together with an indeterminate number of
        additional shares which may be necessary to adjust the number of shares
        reserved for issuance under the Plan as a result of any future stock
        split, stock dividend or similar adjustment of the outstanding Common
        Stock, as provided in Rule 416(a) under the Securities Act.
<PAGE>   2

             PART II. INFORMATION REQUIRED IN REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

        The documents listed below are incorporated by reference in the
Registration Statement. In addition, all documents subsequently filed by
Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities
Exchange Act of 1934, as amended ("Exchange Act") prior to Registrant's filing
of a post-effective amendment which indicates that all securities offered have
been sold or which deregisters all securities then remaining unsold, shall be
deemed to be incorporated by reference into this Registration Statement and to
be a part hereof from the date of filing of such documents.

        (a) The Registrant's Annual Report on Form 10-K for the fiscal year
ended December 31, 1997, filed pursuant to Section 13(a) or 15(d) of the
Exchange Act, which contains audited financial statements for the most recent
fiscal year for which such statements have been filed.

        (b) All other reports filed pursuant to Section 13(a) or 15(d) of the
Exchange Act since the end of the fiscal year covered by the Annual Report on
Form 10-K referred to in (a) above.

        (c) The description of the Common Shares contained in the Registrant's
Prospectus dated June 15, 1998 and included in the Registrant's Registration
Statement on Form S-4 (Registration No.333-53931), including any amendments or
reports filed for the purpose of updating such description.

ITEM 4.  DESCRIPTION OF SECURITIES.

        Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

        The validity of the shares offered pursuant to the Plan will be passed
upon by Graham & Dunn, PC, 1420 Fifth Avenue, 33rd Floor, Seattle, Washington
98101.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        Sections 23B.08.500 through 23B.08.600 RCW contain specific provisions
relating to indemnification of directors and officers of Washington
corporations. In general, the statute provides that (i) a corporation must
indemnify a director or officer who is wholly successful in his defense of a
proceeding to which he is a party because of his status as such, unless limited
by the articles of incorporation, and (ii) a corporation may indemnify a
director or officer if he is not wholly successful in such defense, if it is
determined as provided in the statute that the director meets a certain standard
of conduct, provided when a director is liable to the corporation, the
corporation may not indemnify him. The statute also permits a director or
officer of a 


                                      II-1
<PAGE>   3

corporation who is a party to a proceeding to apply to the courts
for indemnification or advance of expenses, unless the articles of incorporation
provide otherwise, and the court may order indemnification or advance of
expenses under certain circumstances set forth in the statute. The statute
further provides that a corporation may in its articles of incorporation or
bylaws or by resolution provide indemnification in addition to that provided by
the statute, subject to certain conditions set forth in the statute.

        Pursuant to USBN's Bylaws, USBN will indemnify the officers, directors
and employees of USBN with respect to expenses, settlements, judgments, and
fines in suits in which such person has been made a party by reason of the fact
that he or she is or was an officer, director or employee of USBN. No such
indemnification may be given if the acts or omissions of the person are adjudged
to have been taken (or failed to have been taken) in negligence or bad faith.


ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

        Not applicable.

ITEM 8.  EXHIBITS.

<TABLE>
<CAPTION>
 Exhibit 
 Number                     Description
 -------                    -----------
<S>        <C>
   5.1     Opinion of Graham & Dunn, P.C., Registrant's legal
           counsel, regarding legality of the Common Stock being
           registered.
  23.1     Consent of Graham & Dunn (included in Exhibit 5.1).
  23.2     Consent of Moss Adams LLP, USBN's Independent Auditors
  23.3     Consent of McFarland & Alton P.S., USBN's former Independent Auditors.
  24.1     Powers of Attorney (see the Signature Page and certified resolutions
           of the Registrant's Board of Directors).
  99.1     USBN's 1995 Incentive Stock Option Plan and Form of Option Agreement. (1)
</TABLE>

----------
(1) Incorporated by referenced to Exhibit 10.1 of the Registrant's Annual Report
on Form 10-K for the fiscal year ended December 31, 1997.


                                      II-2
<PAGE>   4

ITEM 9.  UNDERTAKINGS.

A.      The undersigned Registrant hereby undertakes:

        (1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this Registration Statement:

                (i) To include any prospectus required by Section 10(a)(3) of
the Securities Act;

                (ii) To reflect in the prospectus any facts or events arising
after the effective date of the Registration Statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the Registration
Statement. Notwithstanding the foregoing, any increase or decrease in volume of
securities offered (if the total dollar value of securities offered would not
exceed that which was registered) and any deviation from the low or high end of
the estimated maximum offering range may be reflected in the form of prospectus
filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
changes in volume and price represent no more than a 20% change in the maximum
aggregate offering price set forth in the "Calculation of Registration Fee"
table in the effective Registration Statement;

                (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the Registration Statement or
any material change to such information in the Registration Statement;

                        Provided, however, that paragraphs (a)(1)(i) and 
(a)(1)(ii) of this section do not apply if the Registration Statement is on Form
S-3, Form S-8 or Form F-3, and the information required to be included in a
post-effective amendment by those paragraphs is contained in periodic reports
filed with or furnished to the Commission by the Registrant pursuant to Section
13 or Section 15(d) of the Securities Exchange Act that are incorporated by
reference in the Registration Statement.

               (2) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

               (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

        B. The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in the Registration Statement shall be deemed to be a
new registration statement relating 



                                      II-3
<PAGE>   5

to the securities offered therein, and the offering of such securities at that
time shall be deemed to be the initial bona fide offering thereof.

        C. Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the Registrant pursuant to the foregoing provisions, or otherwise, the
Registrant has been advised that in the opinion of the Commission such
indemnification is against public policy as expressed in the Act and is,
therefore, unenforceable. In the event that a claim for indemnification against
such liabilities (other than the payment by the Registrant of expenses incurred
or paid by a director, officer of controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Act and will be governed by the final adjudication of
such issue.


                                      II-4
<PAGE>   6

                                   SIGNATURES

        Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Spokane, State of Washington, on the 23rd day of
June, 1998.

                                              UNITED SECURITY BANCORPORATION

                                              By:  /s/ William C. Dashiell
                                                  --------------------------
                                                   William C. Dashiell
                                                   Chief Executive Officer


                               POWER OF ATTORNEY

        Each person whose individual signature appears below hereby authorizes
and appoints William C. Dashiell and Richard C. Emery, and each of them, with
full power of substitution and full power to act without the other, as his true
and lawful attorney-in-fact and agent to act in his name, place and stead and to
execute in the name and on behalf of each person, individually and in each
capacity stated below, and to file any and all amendments to this Registration
Statement, including any and all post-effective amendments.

        Pursuant to the requirements of the 1933 Act, this Power of Attorney has
been signed by the following persons in the capacities indicated, on the 23rd
day of June, 1998.

<TABLE>
<CAPTION>
        SIGNATURE                                         TITLE
        ---------                                         -----

<S>                                                       <C>
/s/ William C. Dashiell                                   Chairman and Chief Executive Officer
----------------------------                              (Principal Executive Officer)
William C. Dashiell 


/s/ Richard C. Emery                                      President, Chief Operating Officer and
----------------------------                              Director
Richard C. Emery                                          


/s/ Chad Galloway                                         Vice President & Chief Financial Officer
----------------------------                              (Principal Financial Officer)
Chad Galloway


/s/ David C. Blankenship                                  Director
----------------------------
David C. Blankenship
</TABLE>


                                      II-5
<PAGE>   7
<TABLE>
<S>                                                       <C>

/s/ Robert J. Gardner                                     Director
----------------------------
Robert J. Gardner


/s/ Dann Simpson                                          Director
----------------------------
Dann Simpson


Norman J. Traaen                                          Director
----------------------------
Norman J. Traaen
</TABLE>


                                      II-6
<PAGE>   8

                                INDEX OF EXHIBITS


<TABLE>
<CAPTION>
 Exhibit 
 Number                                 Description
 -------                                -----------
<S>       <C> 
   5.1    Opinion of Graham & Dunn, P.C., Registrant's legal
          counsel, regarding legality of the Common Stock being
          registered.
  23.1    Consent of Graham & Dunn (included in Exhibit 5.1).
  23.2    Consent of Moss Adams LLP, USBN's Independent Auditors
  23.3    Consent of McFarland & Alton P.S., USBN's former Independent Auditors.
  24.1    Powers of Attorney (see the Signature Page and certified resolutions
          of the Registrant's Board of Directors).
  99.1    USBN's 1995 Incentive Stock Option Plan and Form of Option Agreement. (1)
</TABLE>

----------
(1) Incorporated by referenced to Exhibit 10.1 of the Registrant's Annual Report
on Form 10-K for the fiscal year ended December 31, 1997.


                                      II-7
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 16760}]
{"company-data": {"conformed-name": "UNITED SECURITY BANCORPORATION", "cik": "0000726990", "assigned-sic": "6022", "irs-number": "911259511", "state-of-incorporation": "WA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-58511", "film-number": "98660425"}, "business-address": {"street1": "9506 N NEWPORT HWY", "city": "SPOKANE", "state": "WA", "zip": "99218-1200", "phone": "5094676949"}, "mail-address": {"street1": "9506 N NEWPORT HWY", "city": "SPOKANE", "state": "WA", "zip": "99218-1200"}}
1

      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 1, 1998
                           REGISTRATION NO. 333-_____
 ------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                       ----------------------------------

                                    FORM S-8
                  REGISTRATION UNDER THE SECURITIES ACT OF 1933
                       ----------------------------------

                         UNITED SECURITY BANCORPORATION
             (Exact name of registrant as specified in its charter)
WASHINGTON                                       91-1259511
  (State or other jurisdiction               (I.R.S. Employer Identification Number)
of incorporation or organization)
9506 NORTH NEWPORT HIGHWAY, SPOKANE, WASHINGTON 99218-1200
            (Address of Principal Executive Offices)      (Zip Code)

         UNITED SECURITY BANCORPORATION 1995 INCENTIVE STOCK OPTION PLAN
                              (Full title of plan)

                  Please send copies of all communications to:
RICHARD C. EMERY                                 STEPHEN M. KLEIN
United Security Bancorporation                   Graham & Dunn, P.C.
9506 North Newport Highway                       1420 Fifth Avenue, 33rd Floor
Spokane, WA  98218-1200                          Seattle, WA  98101
(509) 467-6949                                   (206) 624-8300
CALCULATION OF REGISTRATION FEE
-------------------------------------------------------------------------------------------
                                                              Proposed
                                         Proposed maximum     maximum
Title of              Amount             offering             aggregate         Amount of
securities to be      to be              price                offering          registration
registered            registered         per share (1)        price (1)         fee
----------            -----------        -------------        ---------         ---
Common shares,        300,000 (2)        $21.50               $6,450,000        $1,902.75
no par value
--------------------------------------------------------------------------------------------
Notes:
    1.  Estimated solely for the purpose of calculating the amount of the
        registration fee. Pursuant to Rule 457(c) under the Securities Act of
        1933, as amended ("Securities Act"), the price per share is estimated to
        be $21.50 based upon the average of the high ($21.50) and the low
        ($21.50) trading prices of the common stock, no par value per share
        ("Common Stock") of United Security Bancorporation (the "Registrant") as
        reported on the Nasdaq Stock Market on June 30, 1998.
    2.  Shares of Registrant's Common Stock issuable upon exercise of option
        outstanding under the United Security Bancorporation 1995 Incentive
        Stock Option Plan (the "Plan"), together with an indeterminate number of
        additional shares which may be necessary to adjust the number of shares
        reserved for issuance under the Plan as a result of any future stock
        split, stock dividend or similar adjustment of the outstanding Common
        Stock, as provided in Rule 416(a) under the Securities Act.
2

             PART II. INFORMATION REQUIRED IN REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

        The documents listed below are incorporated by reference in the
Registration Statement. In addition, all documents subsequently filed by
Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities
Exchange Act of 1934, as amended ("Exchange Act") prior to Registrant's filing
of a post-effective amendment which indicates that all securities offered have
been sold or which deregisters all securities then remaining unsold, shall be
deemed to be incorporated by reference into this Registration Statement and to
be a part hereof from the date of filing of such documents.

        (a) The Registrant's Annual Report on Form 10-K for the fiscal year
ended December 31, 1997, filed pursuant to Section 13(a) or 15(d) of the
Exchange Act, which contains audited financial statements for the most recent
fiscal year for which such statements have been filed.

        (b) All other reports filed pursuant to Section 13(a) or 15(d) of the
Exchange Act since the end of the fiscal year covered by the Annual Report on
Form 10-K referred to in (a) above.

        (c) The description of the Common Shares contained in the Registrant's
Prospectus dated June 15, 1998 and included in the Registrant's Registration
Statement on Form S-4 (Registration No.333-53931), including any amendments or
reports filed for the purpose of updating such description.

ITEM 4.  DESCRIPTION OF SECURITIES.

        Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

        The validity of the shares offered pursuant to the Plan will be passed
upon by Graham & Dunn, PC, 1420 Fifth Avenue, 33rd Floor, Seattle, Washington
98101.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        Sections 23B.08.500 through 23B.08.600 RCW contain specific provisions
relating to indemnification of directors and officers of Washington
corporations. In general, the statute provides that (i) a corporation must
indemnify a director or officer who is wholly successful in his defense of a
proceeding to which he is a party because of his status as such, unless limited
by the articles of incorporation, and (ii) a corporation may indemnify a
director or officer if he is not wholly successful in such defense, if it is
determined as provided in the statute that the director meets a certain standard
of conduct, provided when a director is liable to the corporation, the
corporation may not indemnify him. The statute also permits a director or
officer of a 

                                      II-1
3

corporation who is a party to a proceeding to apply to the courts
for indemnification or advance of expenses, unless the articles of incorporation
provide otherwise, and the court may order indemnification or advance of
expenses under certain circumstances set forth in the statute. The statute
further provides that a corporation may in its articles of incorporation or
bylaws or by resolution provide indemnification in addition to that provided by
the statute, subject to certain conditions set forth in the statute.

        Pursuant to USBN's Bylaws, USBN will indemnify the officers, directors
and employees of USBN with respect to expenses, settlements, judgments, and
fines in suits in which such person has been made a party by reason of the fact
that he or she is or was an officer, director or employee of USBN. No such
indemnification may be given if the acts or omissions of the person are adjudged
to have been taken (or failed to have been taken) in negligence or bad faith.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

        Not applicable.

ITEM 8.  EXHIBITS.
Exhibit 
 Number                     Description
 -------                    -----------
5.1     Opinion of Graham & Dunn, P.C., Registrant's legal
           counsel, regarding legality of the Common Stock being
           registered.
  23.1     Consent of Graham & Dunn (included in Exhibit 5.1).
  23.2     Consent of Moss Adams LLP, USBN's Independent Auditors
  23.3     Consent of McFarland & Alton P.S., USBN's former Independent Auditors.
  24.1     Powers of Attorney (see the Signature Page and certified resolutions
           of the Registrant's Board of Directors).
  99.1     USBN's 1995 Incentive Stock Option Plan and Form of Option Agreement. (1)
----------
(1) Incorporated by referenced to Exhibit 10.1 of the Registrant's Annual Report
on Form 10-K for the fiscal year ended December 31, 1997.

                                      II-2
4

ITEM 9.  UNDERTAKINGS.

A.      The undersigned Registrant hereby undertakes:

        (1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this Registration Statement:

                (i) To include any prospectus required by Section 10(a)(3) of
the Securities Act;

                (ii) To reflect in the prospectus any facts or events arising
after the effective date of the Registration Statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the Registration
Statement. Notwithstanding the foregoing, any increase or decrease in volume of
securities offered (if the total dollar value of securities offered would not
exceed that which was registered) and any deviation from the low or high end of
the estimated maximum offering range may be reflected in the form of prospectus
filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
changes in volume and price represent no more than a 20% change in the maximum
aggregate offering price set forth in the "Calculation of Registration Fee"
table in the effective Registration Statement;

                (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the Registration Statement or
any material change to such information in the Registration Statement;

                        Provided, however, that paragraphs (a)(1)(i) and 
(a)(1)(ii) of this section do not apply if the Registration Statement is on Form
S-3, Form S-8 or Form F-3, and the information required to be included in a
post-effective amendment by those paragraphs is contained in periodic reports
filed with or furnished to the Commission by the Registrant pursuant to Section
13 or Section 15(d) of the Securities Exchange Act that are incorporated by
reference in the Registration Statement.

               (2) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

               (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

        B. The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in the Registration Statement shall be deemed to be a
new registration statement relating 

                                      II-3
5

to the securities offered therein, and the offering of such securities at that
time shall be deemed to be the initial bona fide offering thereof.

        C. Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the Registrant pursuant to the foregoing provisions, or otherwise, the
Registrant has been advised that in the opinion of the Commission such
indemnification is against public policy as expressed in the Act and is,
therefore, unenforceable. In the event that a claim for indemnification against
such liabilities (other than the payment by the Registrant of expenses incurred
or paid by a director, officer of controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Act and will be governed by the final adjudication of
such issue.

                                      II-4
6

                                   SIGNATURES

        Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Spokane, State of Washington, on the 23rd day of
June, 1998.

                                              UNITED SECURITY BANCORPORATION

                                              By:  /s/ William C. Dashiell
                                                  --------------------------
                                                   William C. Dashiell
                                                   Chief Executive Officer

                               POWER OF ATTORNEY

        Each person whose individual signature appears below hereby authorizes
and appoints William C. Dashiell and Richard C. Emery, and each of them, with
full power of substitution and full power to act without the other, as his true
and lawful attorney-in-fact and agent to act in his name, place and stead and to
execute in the name and on behalf of each person, individually and in each
capacity stated below, and to file any and all amendments to this Registration
Statement, including any and all post-effective amendments.

        Pursuant to the requirements of the 1933 Act, this Power of Attorney has
been signed by the following persons in the capacities indicated, on the 23rd
day of June, 1998.
SIGNATURE                                         TITLE
        ---------                                         -----
/s/ William C. Dashiell                                   Chairman and Chief Executive Officer
----------------------------                              (Principal Executive Officer)
William C. Dashiell 

/s/ Richard C. Emery                                      President, Chief Operating Officer and
----------------------------                              Director
Richard C. Emery                                          

/s/ Chad Galloway                                         Vice President & Chief Financial Officer
----------------------------                              (Principal Financial Officer)
Chad Galloway

/s/ David C. Blankenship                                  Director
----------------------------
David C. Blankenship
II-5
7
/s/ Robert J. Gardner                                     Director
----------------------------
Robert J. Gardner

/s/ Dann Simpson                                          Director
----------------------------
Dann Simpson

Norman J. Traaen                                          Director
----------------------------
Norman J. Traaen
II-6
8

                                INDEX OF EXHIBITS
Exhibit 
 Number                                 Description
 -------                                -----------
5.1    Opinion of Graham & Dunn, P.C., Registrant's legal
          counsel, regarding legality of the Common Stock being
          registered.
  23.1    Consent of Graham & Dunn (included in Exhibit 5.1).
  23.2    Consent of Moss Adams LLP, USBN's Independent Auditors
  23.3    Consent of McFarland & Alton P.S., USBN's former Independent Auditors.
  24.1    Powers of Attorney (see the Signature Page and certified resolutions
          of the Registrant's Board of Directors).
  99.1    USBN's 1995 Incentive Stock Option Plan and Form of Option Agreement. (1)
----------
(1) Incorporated by referenced to Exhibit 10.1 of the Registrant's Annual Report
on Form 10-K for the fiscal year ended December 31, 1997.

                                      II-7