The Travel Reduction Program (TRP) began in 1989 as part of the State of Arizona's response to a court ruling requiring greater efforts to reduce
air pollution. The approximately 80 million commuter miles driven each weekday are a
significant contributor to regional air pollution (ozone, particulate matter). One outcome of the ruling was the legislation of TRP
state statutes that focus on employers and schools. Subsequent revisions to the statute and related
Maricopa County ordinance (P-7) reduced the minimum employee site count to 50.