A Dictionary of Trails for Hikers 

access trail: Any trail that connects the main trail to a town, road, or another trail system.

backcountry trail : A primitive trail (can be open to motorized or nonmotorized users) in an area where there are no maintained roads or permanent buildings.

connecting or side trail: Provides additional points of access to major trails—in particular the nation’s national recreation, scenic, or historic trails per the National Trails System Act.

An abandoned rail line has big-time trail potential: an already existing right-of-way, a usually very well engineered route, a de-facto conservation corridor. Add the advantages of cultural and historical preservation and the contribution to physical fitness a rail converted to a trail makes, and the future seems bright for thousands of miles of disused railway to be put to good use.

Founded in 1986, The Rails-to-Trails Conservancy (RTC) aims to enrich America's communities and countryside with the conversion of abandoned private rail lines into public recreation trails. The Washington D.C.-based group envisions a nationwide network of public trails from former rail lines.