The Convair 240 "Caroline" was the first private aircraft ever used by a candidate during a presidential campaign. This aircraft was used by Senator John F. Kennedy during his successful campaign in 1960 for the Democratic nomination and his election as President. Historians credit this aircraft with providing Kennedy with the narrow margin of victory for it allowed him to campaign more effectively during that very hotly contested race. The "Caroline," named after President Kennedy's daughter, revolutionized American politics; since 1960 all presidential candidates have used aircraft as their primary means of transportation.

Searching for a replacement for the venerable Douglas DC-3 in 1945, American initiated a design requirement for a modern, pressurized, twin-engined, 40-seat pressurized airliner for use in local service. The product was the Convair 240 (with "2" engines and "40" passengers - hence the name). As launch customer, American placed an initial order for 100 of the new CV-240s (later reduced to 75). Fifty more were ordered by Western Airlines, Continental Airlines, Pan American Airways, KLM, and Trans-Australia Airlines. The CV-240 first flew on March 16, 1947 with the first delivery to American on February 28, 1948. It was the first pressurized twin-engined airliner to enter service. A more powerful version built for United Air Lines was introduced in 1952 as the Convair 340. This aircraft featured a longer fuselage to carry 44 passengers as well as a larger wing which gave the aircraft improved high altitude performance. The last piston-engined variant was the CV-440 Metropolitan which incorporated improved sound proofing and optional weather radar. In addition, some 170 340/440s were eventually converted into CV 580s with the replacement of the Pratt & Whitney R-2800 piston engines with Allison 501-D13 turboprops of 3,750 eshp. Sales of the 240/340/440 series to the airlines and the military totaled over 1000 between 1947 and 1956.

The "Caroline" was built in August 1948 and delivered to American Airlines where it served until 1959 when Joseph Kennedy purchased the aircraft and fitted it with an executive interior for his son's 1960 presidential campaign. Though for security reasons President Kennedy rarely used the aircraft after the election, it was used by the family until 1967.

In September 1967, Senator Edward Kennedy approached Secretary Ripley on behalf of his family with the offer to donate the aircraft. Recognizing the eventual historical significant of the aircraft Ripley suggested that NASM accept the aircraft. NASM agreed but was reluctant because of limited storage space. The aircraft was donated on November 17, 1967, during a ceremony at National Airport attended by Ripley and the Kennedy family. It was flown to Andrews AFB and then trucked to Silver Hill where it was dismantled and left outside, deteriorating, until the late 1980s when a curatorial crew and the conservator cleaned the filthy interior. At that time the aircraft was finally moved indoors to safety. For several years, it was the only aircraft left outside.

From 1975 until 1982, the Museum of American History recognized the significance of the "Caroline" by borrowing the interior for their popular "We the People" exhibit. Following the close of the exhibit the interior was lent to the Kennedy Library until it was recently returned.

The Convair 240 is an all metal, low-wing multi-spar monoplane with hydraulically-powered Fowler flaps and was fitted with a retractable tricycle landing gear. The rudder and trailing edges of the elevator were made of fiberglass. Power was provided by two Pratt & Whitney Double Wasp R-2800-CA3 eighteen cylinder air-cooled engines, each producing 2,400 horsepower. Some additional thrust was provided by an exhaust-augmented cooling system. The engines were houses in a clever four-panel clamshell cowling which permitted virtually unrestricted access for maintenance. The pressurized fuselage was circular in cross-section and sat 40 passengers four abreast in ten rows. The cockpit was designed for two pilot operation.

The Convair 240 has a span of 91 feet, 9 inches, a length of 74 feet 8 inches, a height of 26 feet 11 inches, and a wing area of 817 square feet. Empty weight of the original design was 25,445 pounds with a maximum gross weight of 42,500 pounds. Maximum speed was 315 miles per hour, maximum cruise was 280 miles per hour, a ceiling of 16,000 feet, a range of 1,200 miles, and an initial climb rate of 1,520 feet per minute. The aircraft could carry between 1,000 and 1,500 U.S. gallons of fuel.