General Aviation Airports: A National Asset documents an 18-month study of the nearly 3,000 general aviation (GA) airports, heliports, and seaplane bases identified in the FAA’s National Plan of Integrated Airport Systems (NPIAS). This in-depth analysis highlights for the traveling public the pivotal role GA airports play in our society, economy, and the aviation system.
http://www.faa.gov/airports/planning_capacity/ga_study/media/2012AssetReport.pdf