Capital Airlines was a commercial airline for the eastern, southern, southeastern, and midwestern United States from 1936 to 1961. In the 1950s, it was the fifth largest airline in the United States. The airline was the first to offer service from the west to Washington D.C., coach class service, in-flight television, and jet-powered commercial aircraft.

Capital Airlines can trace its roots back to the Clifford Ball Airline which operated out of Pittsburgh’s Bettis Field Airport. The Clifford Ball Airline was established in 1926 by Clifford Ball (1892-1972), who founded the country’s first air mail service and a pioneer of commercial aviation.

On April 26, 1927 the first air mail flew from Bettis Field to Cleveland. In 1928, Clifford Ball Airlines began a passenger service. In 1929, Ball coined the phrase “Path of the Eagle” and began a passenger route from Cleveland to Washington. Clifford Ball Airline was sold to Pittsburgh Aviation Industries Corp (PAIC) in 1930, and became Pennsylvania Air Lines.

Due to the Air Mail Scandal of 1934, the company went through a number of changes. By 1935, C. Bedell Monro (1901-1972) was President. The company received an air mail contract and went on to recover from the scandal. Another company also received an air mail contract in the same region, Central Airlines. The two airlines competed in vigorous price wars and both began to suffer financially. In 1936, Pennsylvania Air Lines and Central Airlines merged becoming, Pennsylvania Central Airlines (PCA). Bedell remained President of the company.

In 1941, PCA moved its headquarters to Washington D.C. and therefore dubbed its fleet as “The Capital Fleet” and “Capitaliners”. During World War II, the company experienced significant expansion and growth. After the war the company began to suffer financially again.

Monro resigned from PCA in October of 1947 and James H. “Slim” Carmichael (1907-1983) was named his successor. Monro stated it was “grave difference of opinion” over the company's management that prompted his resignation.

Carmichael was a former barnstormer, stunt flier, crop duster and an early airmail pilot. He learned to fly at the age of nineteen. He had been with the company since the beginning. Carmichael is credited with rescuing the airline from bankruptcy when taking over as President and reorganizing the company under its new name. In early 1947, PCA unofficially changed its name in advertisements to Capital and designed a new logo, however, the name change wasn’t approved by the CAB (Civil Aeronautics Board) until April of 1948.

In November 1948, the Nighthawk service began. It was a four cent-a-mile nightly air service between New York and Chicago. It was a “coach” class, no frills flight. There were no meals, pillows, blankets, or other amenities, which made it very cost-effective for passengers. The service was a successful and profitable for Capital Airlines. After long use of the DC-3 and DC-4 aircrafts, Capital Airlines invested heavily in British-built jet and prop-jet airliners. In 1955, the company purchased forty Vickers Viscounts. These were the first commercial passenger prop-jet airliner. Capital Airlines went on to own sixty-seven Viscounts.

Carmichael resigned in 1958 for “personal reasons” with no further comment from Capital or Carmichael. He was replaced by a retired U.S. Air Force Major General, David Hodges Baker III (1907-2003).

By the late 1950s, the company began to falter due to increased debt. In 1958, Capital employees went on strike for a month. In 1958 to 1960, they had five aircraft accidents. In 1960, Vickers-Armstrong filed a foreclosure suit on the entire Capital Airlines Viscount fleet. In August 1960, a merger of Capital and United was proposed. On June 1, 1961, United Airlines purchased Capital Airlines and took over its Viscount fleet.

In 1981, the former employees of Capital Airlines founded the Capital Airlines Association. The association had approximately 1,500 members and held an annual picnic. The last picnic was held in 2004 and the association disbanded due to decline in membership.