This index of documents includes the hearings, committee reports, bills, and other related materials pertaining to the National Trails System Act of 1968 (P. L. 90-543) and its subsequent amendments, through P. L. 111-11 (March 30, 2009). The documents are listed in order by public law number. Sources in [ ]s have not yet been explored. (There may be additional sources as yet not found.) Documents are grouped to show the evolution from bill introduction to passage into law. In bills which contain sections unrelated to the National Trails System Act, those debates, hearings, and reports which do not pertain to the National Trails System Act have been excluded.