The design was based on the Budd Hi-Level cars used by the Santa Fe Railway on its El Capitan trains.

On May 1, 1971, Amtrak assumed control of almost all private-sector intercity passenger rail service in the United States, with a mandate to reverse decades of decline.

[5] The Budd Company built these between 1954 and 1964; the bilevel design, with its superior views and smooth riding characteristics, was well-suited to the long distances in the west.

The design was finished by mid-1974 and Amtrak invited four companies to bid on its construction: Boeing, Budd, Pullman-Standard, and Rohr.

[7] Amtrak ordered 235 Superliner I cars from Pullman-Standard on April 2, 1975, with deliveries scheduled for between January 1977 and June 1978.

[b] A public unveiling took place at Union Station in Chicago on October 11, 1979, followed by a short trip over the Burlington Northern Railroad to Lisle.

[17] Amtrak's first choice for Superliner assignments had been the financially troubled Floridian, a Chicago–Florida long-distance train, but the two years' delay in delivery scuppered these plans.

[22] With the Empire Builder in operation, Amtrak began re-equipping the remaining long-distance trains in the west.

The Southwest Limited, formerly the Super Chief, traveled the same route as the El Capitan, whose Hi-Level cars had inspired the design.

[33] Ultimately Via chose to rebuild its Budd cars to use head end power (HEP) instead of ordering new equipment.

[39] A project to enlarge the First Street Tunnel in Washington, D.C., enabled the Chicago–Washington Cardinal to begin using Superliners in September 1995; these were withdrawn in 2002 because of equipment shortages.

[c] In 2017, Amtrak identified a need to replace the Superliners, noting that each car traveled the equivalent of "seven trips around the world" every year.

This was more reliable than the steam heat used by the Hi-Levels,[47][19] whose own heaters and diesel generators would eventually be replaced by HEP equipment.

[49] To this day, inadequate tunnel clearances in and around New York City and Baltimore prevent the use of Superliners on Amtrak's busiest line, the Northeast Corridor.

[52][53] The Superliner IIs ride on GSI-G70 outboard bearing trucks, also found on the Horizon single-level cars.

[55][d] The Superliner I cars originally stored waste in tanks, then macerated and dumped it along the tracks once the train had attained a preset speed.

[57] Growing public concern about such dumping led Amtrak to order its Superliner IIs with a full-retention system.

[59] The New York Times described the Superliner I interior color scheme as "soft hues of beige, rust, brown and green".

[67] After a grade crossing accident in 1999, the Transportation Safety Board of Canada faulted the layout on the lower level; the exterior door, when opened and locked in position, prevented egress from the wheelchair-accessible bathroom.

The lower level contains opposed family and accessible bedrooms, four toilets, four roomettes, and a luggage rack.

A dumbwaiter is used to bring food and drink to the dining level, as well as to return dishes, glasses, and cutlery for washing.

[94] Dubbed the "Cross-Country Cafe", they were intended to reduce food service losses by replacing both a traditional dining car and the Sightseer lounge on long-distance trains.

The other side remained dedicated to traditional diner seating, but the standard two-by-two tables were replaced by booths.

[66] On some trains, Amtrak makes the roomettes closest to the upper level end door available for sale to passengers.

They were not equipped for the volumes of passenger loading and unloading found on corridor routes, nor did they have amenities designed for these shorter trips.

[99] The 1990 passage of California propositions 108, 111 and 116 authorized the sale of nearly $3 billion in bonds for the creation of rail services across the state.

[100][99] Proposition 116 required the California Department of Transportation (Caltrans) to create specifications for standardized railcars and locomotives that would be suitable for rail operations across the state.

The California Cars comply with the Americans with Disabilities Act of 1990, with wheelchair lifts and accessible seating on the lower levels.

[102] Caltrans and the Illinois Department of Transportation ordered 130 of these Next Generation Bi-Level Passenger Rail Cars from Sumitomo (with Nippon Sharyo as the builder) in 2012.

Increasing the buff strength would require a complete redesign of the car, and would delay delivery beyond the expiration of a $220 million American Recovery and Reinvestment Act of 2009 (ARRA) grant that funded the order.