The Columbian between Jersey City and Washington was the first air-conditioned passenger train in North America. Air-conditioned equipment began operating on the train on May 24, 1931. IN 1937 the B&O re-equipped the Columbian with cars from the Royal Blue. On December 19, 1941 the B&O extended the Columbian from Washington to Chicago. To support the longer service the Columbian again received cast-offs from the Royal Blue, plus other equipment. The Columbian operated in tandem with the all-Pullman Capitol Limited, running thirty minutes behind. The Capitol Limited conveyed the Columbians coaches between Jersey City and Washington. During World War II the Columbians consist swelled to 14 cars. In 1949, a brand new lightweight Columbian train set for travel between Baltimore, Maryland, via Washington to Chicago was built. The consists were ordered from Pullman-Standard for April, 1949 delivery and these two train sets have the distinction of being the only all-new consists built for the B&O in the postwar period. These two eight-car streamlined trains were the first trains in the eastern U.S. to be equipped with dome cars, the "Strata-Dome". Although the pair were intended as a daytime operation between Chicago and Baltimore by way of Washington the two new trains entered overnight service May 5, 1949. In the 1950s saw a wave of consolidations as the B&O's passenger services contracted. The Columbian and Ambassador began joint operation between Washington and Willard, Ohio on January 10, 1954. On December 1, 1957, the Columbians dining car stopped operating west of Willard. On April 26, 1958, the B&O discontinued all passenger service between Jersey City and Baltimore, Maryland, and thereafter the eastern terminus of the Columbian was Baltimore. At the same time the Columbian and Capitol Limited began joint operation between Washington and Baltimore. On October 26, 1958, this joint operation extended all the way to Willard, ending the independence of both trains. The B&O dropped the Columbian name altogether on April 26, 1964. When Amtrak took over train service on May 1, 1971, the B&O's combined Capitol Limited - Columbian was discontinued, along with all other B&O long-distance passenger trains.
Equipment
In December 1937 the Columbian received equipment originally rebuilt in 1935 for the Royal Blue. These were heavyweight cars given a streamlined appearance. The consist included a baggage-coach, three coaches, a coach-buffet, diner-lunch car, a parlor car which included a drawing room, and a buffet-observation car. The December 1941 re-equipping for long-distance service again involved refurbished Royal Blue equipment, although with long-distance-specific changes such as reducing the number of seats in the coaches. Each consist included a baggage-dormitory-buffet lounge, three coaches, a 46-seat coach with a stewardess' room, a dining car, and a buffet-observation car. The B&O removed the buffet-observation cars in 1943. Diesel locomotives began handling the Columbian in 1945. Pullman-Standard constructed two lightweight consists for the 1949 iteration of the Columbian. Each consist included a baggage-dormitory-coffee shop, four coaches, Strata-Domedome coach, dining car, and tavern-observation car. Each coach could seat 56; the dining car had seating space for 36. The new Strata-Domes could seat 24 in the dome area and 40 in revenue seating below, along with two lounges. ; First consist
#1350 Harpers Ferry baggage-dormitory-coffee shop
#5500 Connellsville coach
#5502 Gary coach
#5550 High Dome Strata-Dome dome coach
#1090 Akron dining car
#5504 Martinsburg coach
#5506 New Castle coach
#3315 Chicago tavern-observation
; Second consist
#1351 Silver Spring baggage-dormitory-coffee shop
#5501 Cumberland coach
#5503 La Paz coach
#5551 Sky Dome Strata-Dome dome coach
#1091 Pittsburgh dining car
#5505 McKeesport coach
#5507 Youngstown coach
#3316 Washington tavern-observation
The B&O added two slumbercoaches to the Columbian's equipment pool in 1958: the Slumberland and Dreamland. The Columbian lost its tavern-observation cars after it began join operation with the Capitol Limited.