is the Northeast Corridor between Washington, Baltimore, Philadelphia, New York City, and Boston, with significant branches in Connecticut and Massachusetts. The corridor handles frequent passenger service that is both Amtrak and commuter. New York City itself is noteworthy for high usage of passenger rail transport, both subway and commuter rail (Long Island Rail Road, Metro-North Railroad, New Jersey Transit). The subway system is used by one third of all U.S. mass transit users. Chicago also sees high rail ridership, with a local elevated system, one of the world's last interurban lines, and fourth most-ridden commuter rail system in the United States: Metra. Other major cities with substantial rail infrastructure include Philadelphia's SEPTA, Boston's MBTA, and Washington, D.C.'s network of commuter rail and rapid transit. Denver, Colorado constructed a new electrified commuter rail system in the 2000s to complement the city's light rail system. The commuter rail systems of San Diego and Los Angeles, Coaster and Metrolink, connect in Oceanside, California. The San Francisco Bay Area additionally hosts several local passenger rail operators, the largest of which are Caltrain, the Altamont Corridor Express, Sonoma–Marin Area Rail Transit, and Bay Area Rapid Transit. Privately run inter-city passenger rail operations have also been restarted since 2018 in south Florida, with additional routes under development. Brightline is a higher-speed rail train, run by All Aboard Florida. It began service in January 2018 between Fort Lauderdale and West Palm Beach; its service was extended to Miami in May 2018, with an extension to Orlando International Airport planned by 2022. Brightline has also proposed a further extension of its service from Orlando to Tampa via Walt Disney World, and a high-speed rail service from Victorville, California to Las Vegas. In addition, the Texas Central Railway is currently developing plans for a proposed greenfield high-speed rail line using Japanese Shinkansen trains between Dallas and Houston. Construction was expected to begin in 2020 for a 2026 opening, but a major lawsuit delayed the project and as of February 2023 there are no signs of construction activity. Car types The basic design of a passenger car was standardized by 1870. By 1900, the main car types were: baggage, coach, combine, diner, dome car, lounge, observation, private, Pullman, railroad post office (RPO) and sleeper. 19th century: First passenger cars and early development The first passenger cars resembled stagecoaches. They were short, often less than long, tall and rode on a