The Moving Ahead for Progress in the 21st Century Act (MAP-21) reauthorized the Recreational Trails Program (RTP) through Federal fiscal years 2013 and 2014 as a setaside from the Transportation Alternatives Program. The amount set aside is equal to the State's FY 2009 RTP apportionment. (From FY 1993 through FY 2012, the RTP funds were distributed to the States by legislative formula: half of the funds were distributed equally among all States, and half were distributed in proportion to the estimated amount of nonhighway recreational fuel use in each State.).
The RTP funds come from the Federal Highway Trust Fund, and represent a portion of the motor fuel excise tax collected from nonhighway recreational fuel use: fuel used for off-highway recreation by snowmobiles, all-terrain vehicles, off-highway motorcycles, and off-highway light trucks. The estimates are based on a model developed by the Oak Ridge National Laboratory: http://cta.ornl.gov/cta/publications.shtml#1999.