Here's how to change the base layer on any map:

1. Open the map you are interested in.
   
2. Click the white drop-down box at the bottom of the legend.
   
   
   
3. Choose the base layer that you want to use.

*Note: This base layer will stay as long as you have the map open. Once you close and re-open the map, it will go back to its default map background layer, which is set by the site administrator.