• First commercial aircraft able to fly non-stop westbound across the United States against the jet stream.
• Fastest piston-powered commercial airplane in 1954. With a top speed of 410 miles per hour, and average cruising speed of 365 mph, flew almost 25 to 30 mph faster than the  Douglas DC-6 and  Lockheed Constellation.
• Weight savings of approximately 200 pounds per aircraft with the first use of titanium, a heat-resistant and lightweight metal, on commercial aircraft.

The longer length of the DC-7 and DC-7B fuselage (over eight feet more than the  DC-6), allowed room for an eight-passenger Sky Room, with facing seats, and a five-seat Sky Lounge, in addition to two main cabins.

Delta's DC-7 and DC-7B initially held 69 passengers in all first-class seating, except for four DC-7B which were delivered in 1957 with all-coach configuration for 90 passengers. 

Improvements in air conditioning and sound proofing provided additional comfort. Windows in critical noise areas had an added third pane of glass, free-floating in rubber, sandwiched between the usual two panes, to reduce noise. 

The "luxurious interior" of the DC-7 in 1954, featured rich colors: forest green fabric seats with gray leather arms, a gray-green ceiling and dark carpet. The lounge was gray-green with bright coral upholstery.

First delivered in 1957, the DC-7B model had a brighter interior with tan, white, aqua and turquoise fabrics and leathers accented with gold and silver. Gold window curtains depicted scenes along Delta's routes, "setting the mood for a Millionaire Dream Vacation in such gay holiday spots as New Orleans, Jamaica and Havana."

The DC-7 was the last piston-engine airplane ordered by Delta. Deliveries began in February and March 1954.

Delta DC-7 service started April 1, 1954, from Chicago to Miami. The inaugural aircraft was DC-7, N4871C, Ship 701, named "Royal Biscayne."

The captain of that inaugural flight was C.H. "Charlie" Dolson, Delta's vice president - flight operations. Capt. Dolson, hired as a Delta pilot in 1934, later became Delta's president in 1965, and the airline's second CEO in 1966, following the death of founder  C.E. Woolman.

On April 1, 1955, Delta operated the world's first intercontinental DC-7 scheduled flight, with service from New Orleans to San Juan, Puerto Rico, and Caracas, Venezuela.

Initial service: Chicago-Miami from April 1-25, 1954. Nonstop flying time between Chicago and Miami was 3 hours and 40 minutes in the Delta DC-7, compared to 4 hours in the  DC-6.

On April 25, 1954, DC-7 service expanded southbound between Chicago, Cincinnati, Atlanta and Miami; northbound, from Miami and Atlanta and Chicago. On June 1, 1954, Delta added DC-7 service from Chicago to Houston and St. Louis.

Later DC-7 service included San Juan and Caracas from New Orleans; and to Washington, DC and New York from Atlanta, Houston and Dallas. By 1958, Delta's DC-7 and DC-7B fleet served 18 major cities and accounted for 53% of all Delta seat miles flown.

Transcontinental service to California began in 1961. 

Delta received its first DC-7B on June 14, 1957.

The -7B model was a slightly longer-range version of the DC-7 with higher gross weight. Optional saddle fuel tanks in the engine nacelles increased fuel capacity for additional range, but Delta, like all U.S. operators of the -7B except  Pan American, did not install them.

Of the 21 DC-7 aircraft that Delta flew, 10 were Model 7Bs (fleet numbers Ship 712-Ship 721).

Delta originally ordered eleven DC-7Bs, but when the airline took delivery of the prototype DC-7B from Douglas on December 10, 1955, it was certified as a DC-7 (registration N4881C, Ship 711).

Delta started jet service in 1959, and as its fleet became increasing jet-powered, started selling its DC-7 aircraft in 1966. In 1967, Delta retired all but four aircraft of its Douglas DC-7 fleet.

Delta operated its final DC-7 service as of February 1, 1968.

From March 1954 to February 1968, Delta flew the DC-7 for a total of 604,623 hours and 24 minutes.