As published in the Title III regulations (28 CFR Part 36, revised July 1, 1994) issued by the Department of Justice. The ADA Standards for Accessible Design are in Appendix A of the Title III Regulations
1991 ADA Standards for Accessible Design ( PDF) (4.5 MB file)
The Department of Justice published revised regulations for Titles II and III of the Americans with Disabilities Act of 1990 (ADA) in the Federal Register on September 15, 2010. These regulations adopted revised, enforceable accessibility standards called the 2010 ADA Standards for Accessible Design "2010 Standards".
On March 15, 2012, compliance with the 2010 Standards will be required for new construction and alterations. In the period between September 15, 2010 and March 15, 2012, covered entities may choose between the 1991 Standards (without the elevator exemption for Title II facilities), the Uniform Federal Accessibility Standards (Title II facilities only), and the 2010 Standards.