Dawson was the first African American to chair a committee in the United States Congress, when he chaired the Committee on Expenditures in Executive Departments. He served as Chair of that committee and its successor for most of the years between 1949 and 1970. After 1952, Dawson also became closely aligned with the Democratic city machine in Chicago, collaborating often with Mayor Richard J. Daley. In this role, he focused on patronage and services for his constituents. He gave no support to the efforts of Martin Luther King Jr. to shake up city politics in the late 1960s.