The Federal Motor Carrier Safety Regulations (FMCSRs) generally apply to all employers, employees, and commercial motor vehicles involved in the transportation of passengers across state lines and any other operation deemed to be operating in interstate commerce. The major categories of passenger-carrying vehicles subject to regulation include for-hire motor carriers, private motor carriers of passengers (both business and non-business), and school buses. The FMCSRs and the requirements of the Americans with Disabilities Act exist at all levels of passenger transport, from small private church groups to large tour operators, with certain exceptions.