Oklahoma's 3rd congressional district is the largest congressional district in the state, covering an area of 34,088.49 square miles, over 48 percent the state's land mass. The district is bordered by New Mexico, Colorado, Kansas, and the Texas panhandle. Altogether, the district includes a total of 32 counties, and covers more territory than the state's other four districts combined. It is one of the largest districts in the nation that does not cover an entire state.

Frank Dean Lucas is an American politician serving as the U.S. representative for Oklahoma's 3rd congressional district since 2003, having previously represented the 6th district from 1994 to 2003. A member of the Republican Party, Lucas has chaired the House Committee on Science, Space and Technology since 2023. His district, numbered as the 6th from 1994 to 2003, is Oklahoma's largest congressional district and one of the largest in the nation that does not cover an entire state. It covers 34,088.49 square miles and stretches from the Panhandle to the fringes of the Tulsa suburbs, covering almost half of the state's land mass. Lucas is the dean of Oklahoma's congressional delegation.