The Base MapDrop Down Menu is shown below.
There are seven (7) base map options: Topographic, Satellite, Terrain, Hybrid, DIST2012, EVT, and FBFM40. The first 4 of these are map services from ESRI (http://www.esri.com/data/find-data#basemaps).
The topographic basemap includes boundaries, cities, water features, physiographic features, parks, landmarks, transportation, and buildings.
The satellite basemap presents high resolution imagery for the the United States. This map was last updated September 2016 (https://www.arcgis.com/home/item.html?id=10df2279f9684e4a9f6a7f08febac2a9).
The terrain basemap features shaded relief imagery, bathymetry, and coastal water features ( http://www.arcgis.com/home/item.html?id=c61ad8ab017d49e1a82f580ee1298931).
The hybrid basemap is a a blend of satellite and high-resolution aerial imagery with political boundaries, roads, and some labels; this map was last modified December 2014 ( http://www.arcgis.com/home/item.html? id=86265e5a4bbb4187a59719cf134e0018 ).
Three of the base maps are based on the LANDFIRE spatial data products: DIST2012, EVT 2012, and FBFM40 2012.