Click on a location on the U.S. map.  The right panel will display a zoom of that region.  To view sites for a given location, click on a dot (if you hover your mouse over a cluster of dots, a tool tip will list the sites within that cluster).  Scroll down for search results.  In this example, the map query resulted in 5 sites in the Jack Pine series.  Click on a site thumbnail to view associated site information and data tables. 

Photo series sites were often located close together and may appear as a tight cluster of dots.  If you move your cursor above each dot or cluster of dots a box indicating which sites are represented will appear.