Amtrak has used a variety of paint schemes (liveries) on its rolling stock since taking over intercity passenger rail service in the United States in 1971. A series of seven schemes termed Phases, first introduced in 1972, have seen the widest use. Phases primarily use geometric arrangements of red, white, and blue—the national colors of the United States—part of Amtrak's patriotic visual identity.
Amtrak began operations in May 1971 with a mixture of equipment still painted in the distinct colored liveries of the freight railroads that relinquished their passenger service to Amtrak. The company retained the equipment that it determined to be in the best condition, and elected not to keep the same rolling stock on the same routes. Since this resulted in trains with mismatched liveries, which contrasted with the previous coordinated liveries, that period was later known as the Rainbow Era.
To build the brand of Amtrak as a unified passenger railroad, the rolling stock was gradually repainted into a new system-wide livery starting around 1972. Successive liveries are known as Phases and are sequentially numbered using Roman numerals – a nomenclature that began with model railroaders and was later officially adopted by Amtrak. Most current locomotives use the 2000-introduced Phase V, while passenger cars use the 2002-introduced Phase VI (or Phase IVb). A modified Phase III scheme was introduced for some equipment in 2013. Non-revenue equipment uses bright lime green or a variation of Phase V.
Some routes financially supported by individual states use service-specific liveries to provide a more regionalized distinction. These include the three Amtrak California routes, eight Amtrak Midwest services, the Cascades, and the Piedmont. Amtrak has repainted equipment in unique livery for special uses, including its 40th anniversary in 2011 and to promote the Operation Lifesaver safety campaign. Equipment has also been wrapped for advertising promotions. When testing equipment from other railroads, Amtrak has mostly kept existing livery, though some longer-term tests used Phase schemes.