While the Americans with Disabilities Act (ADA) of 1990 requires public transit services, under specific conditions, to be accessible to persons with special needs, it did not impose a statutory deadline for fleet accessibility. The ADA did require all key stations to be accessible by July 1993 but allowed the Federal Transit Administration (FTA) to grant an extension up to July 2020 for stations requiring structural modifications to bring them into compliance.
FTA has collected data on ADA accessibility since 1993. An accessible station is one that provides ready access and does not have physical barriers that prohibit and/or restrict access by individuals with disabilities, including those who use wheelchairs.
U.S. Department of Transportation, Federal Transit Administration, FY 2002 Performance Plan (Washington, DC: 2003).