old_contents: """
  U.S. state capitals overlayed on a map of the U.S
  ================================================-
  This is a geographic visualization that shows US capitals
  overlayed on a map.
  """
  
  import altair as alt
  from vega_datasets import data
  
  states = alt.UrlData(data.us_10m.url,
                       format=alt.TopoDataFormat(type='topojson',
                                                 feature='states'))
  capitals = data.us_state_capitals.url
  
  # US states background
  background = alt.Chart(states).mark_geoshape(
      fill='lightgray',
      stroke='white'
  ).properties(
      projection={'type': 'albersUsa'},
      width=800,
      height=500
  )
  
  # State capitals labeled on background
  points = alt.Chart(capitals).mark_text().encode(
      alt.Text('city', type='nominal'),
      alt.X('lon', type='longitude'),
      alt.Y('lat', type='latitude'),
  )
  
  chart = background + points
  
new_contents: """
  U.S. state capitals overlayed on a map of the U.S
  ================================================
  This is a layered geographic visualization that shows US capitals
  overlayed on a map.
  """
  
  import altair as alt
  from vega_datasets import data
  
  states = alt.UrlData(data.us_10m.url,
                       format=alt.TopoDataFormat(type='topojson',
                                                 feature='states'))
  capitals = data.us_state_capitals.url
  
  # US states background
  background = alt.Chart(states).mark_geoshape(
      fill='lightgray',
      stroke='white'
  ).properties(
      projection={'type': 'albersUsa'},
      width=800,
      height=500
  )
  
  # State capitals labeled on background
  points = alt.Chart(capitals).mark_text(dy=-5, align='right').encode(
      alt.Text('city', type='nominal'),
      alt.X('lon', type='longitude'),
      alt.Y('lat', type='latitude'),
  )
  
  chart = background + points + points.mark_point(color='black')
  
subject: Add points for capital locations>