I-235 through Oklahoma City was established as an Interstate route by American Association of State Highway and Transportation Officials (AASHTO) on July 13, 1976. The route was previously submitted to the Federal Highway Administration (FHWA) for inclusion in the Interstate System on November 5, 1975. FHWA responded favorably to the request on May 13, 1976:
we conditionally approve under the provisions of 23 U.S.C. 139(a) the addition to the Interstate System of the 1.5-mile northern segment of the Central Expressway in Oklahoma City. We also conditionally approve under the provisions of 23 U.S.C. 103(e)(1) the addition to the Interstate System of the 3.2-mile southern segment of the Central Expressway.
The FHWA approval authorized the use of Federal Interstate Funds for constructing the 3.2 miles of the Central Expressway extending south from NW 36th Street to I-35/40. The remainder of the Central Expressway north to then-I-240 was essentially complete to Interstate standards.
The Centennial Expressway section of I-235, from I-35/40 north to NW 36th Street, opened to traffic on April 22, 1989, coinciding with the 100-year anniversary of the “Oklahoma Land Run.” The section beyond N 36th Street was built in the late 1960s and is considered part of Broadway.1
U.S. 77 originally navigated through central Oklahoma City along surface streets. Overlapping with U.S. 62, U.S. 77 partitioned along the couplet of Robinson Avenue / Broadway through Downtown to NE 23rd Street east (U.S. 270). 23rd Street took U.S. 62-72-270 east to the State Capitol and Lincoln Boulevard. There U.S. 77 combined with U.S. 66 Business north to Grand Boulevard, the predecessor to Interstate 44 and the Northeast Expressway.
Construction was underway by 1962 for Broadway Extension south from U.S. 66 (Grand Boulevard) topping Park. Upon completion, the freeway spur south from U.S. 66 was unnumbered. What would eventually become a part of I-235 south to I-35 and I-40 was originally referenced as the Capital Freeway. The Capital Freeway was proposed to tie into Lincoln Boulevard south of the Capitol on the 1976 Official Oklahoma Highway Map.
U.S. 77 was initially realigned from using Robinson Avenue southbound to follow just Broadway through Downtown. The relocation from 5th Street SW north to 23rd Street NW was approved by AASHTO on October 28, 1978. The 1981 Official Oklahoma Highway Map shows U.S. 77 changed again, following Reno Avenue east to Lincoln Boulevard north. Upon completion of the Centennial Freeway, U.S. 77 shifted a final time to overlap with all of Interstate 235.