The Eliot Avenue portion of the line was a separate Triboro Coach route, which began operating in 1940 as alternate branches of the Q45 (now the southern half of the Q47).

The Q38's terminals at Corona and Forest Hills are less than 0.5 miles (0.80 km) apart and located within a block of the Long Island Expressway to the north and south respectively.

Here, the route serves the 63rd Drive–Rego Park station of the IND Queens Boulevard Line and the Rego Center shopping complex.

[9][7] The Q38 continues west to Fresh Pond Road, in Ridgewood where it then turns north and then east onto Eliot Avenue, and back into Middle Village again.

The Penelope Avenue route was originally started by the Affiliated Bus Transit Corporation on June 17, 1934,[1][2][13] given the designation "Q-38" by the fall of that year.

[14] The original Q38 route began in East Elmhurst near Flushing Bay, running south down 108th Street, west on 62nd Drive and Apex Place.

[14][15][16] Affiliated Bus operated the route on several temporary permits,[1][2][17] before being granted a five-year contract from the city in November 1934.

[25] In July, the president of Triboro Coach said his company was preparing an application for a franchise modification to the New York City Board of Estimate (NYCBOE) for this extension.

[26] The director of the Bureau of Franchises stated that the Chairman of the Board of Transportation had forwarded the Ridgewood Chamber of Commerce's request to his department.

[28][29] In January 1949, president of Triboro Coach announced that the expected arrival of ten new buses by the end of the month could make it possible for the extension to be implemented, contingent on a temporary permit.

Triboro was also asking the Board of Estimate to legalize an extension on its northern end to the Rego Park Emergency Veterans Housing Project at 98th Street and 59th Avenue that had been operating on a temporary permit.

[43] The Eliot Avenue/Corona branch of the Q38 would be split into a new route, the Q14, running from the Fresh Pond Road station in Ridgewood to Ditmars Boulevard in East Elmhurst.

The Q38 designation would still apply to the Rego Park branch, which would terminate at Metropolitan Avenue and Fresh Pond Road.

In Middle Village, the Q38 would be straightened, running along Juniper Boulevard South from 69th Street to Dry Harbor Road.

[47]: 122–123  The Rego Park branch of the Q38 would retain its existing zigzag routing along Juniper Valley Road and Penelope Avenue.

[50] On January 29, 2025, the current plan was approved by the MTA Board, and the Queens Bus Redesign will go into effect by Labor Day.