Its type certificate was issued on June 30, 1960, and it entered service with United Airlines on July 5, 1960.

[citation needed] As a derivative, the 720 had low development costs, allowing profitability despite relatively few sales.

Compared to the 707-120, it has a length reduced by 8.33 feet (2.54 m), a modified wing and a lightened airframe for a lower maximum takeoff weight.

Originally designed to be powered by four Pratt & Whitney JT3C turbojets, the initial 720 could cover a 2,800 nautical miles [nmi] (5,200 km; 3,200 mi) range with 131 passengers in two classes.

It could seat 156 passengers in one class over a 3,200 nautical miles [nmi] (5,900 km; 3,700 mi) range.

[6] The new model was designed to a lower maximum takeoff weight with a modified wing and a lightened airframe.

The wing modifications included Krueger flaps outboard of the outboard engines, lowering take-off and landing speeds—thus shortening runway length requirements—and a thickened inboard leading edge section, with a slightly greater sweep.

[12] As a modification of an existing model, the 720 had minimal research and development costs, which allowed it to be successful despite few sales.

The normal practice for Boeing 720 aircraft was to start the number three (inner starboard) engine first, then disconnect ground power and air.

On January 2, 1962, Pakistan International Airlines′ first Boeing 720B – a Boeing 720-040B (registration AP-AMG) piloted by Captain Abdullah Baig and copilot Captain Taimur Baig – set a world record during the London-to-Karachi leg of its delivery flight to Pakistan for speed over a commercial air route, making the flight in 6 hours 43 minutes 55 seconds at an average speed of 938.78 km/h (583.33 mph).

At least one of the landing sites was Yokota AB, Japan, before the troops traveled to their final destinations.

[20] The first 720 (N7201U) was later renamed "The Starship" and became a private charter jet used mainly by touring rock bands.

The seating capacity was reduced and a bar with a built-in electric organ was added, along with beds, a shower, a lounge area, a TV, and video cassette player.

[21] Honeywell operated the last Boeing 720 in the United States, flying out of Sky Harbor Airport in Phoenix.

It was purchased by PWC in December 1985 and between October 1986 and January 1988 it was modified for use as a flying engine test bed.

[4] In May 2012, the former PWC 720 was flown to CFB Trenton, Ontario, to be put on display at the National Air Force Museum of Canada.