 Senator in Montana history, and the senator who shepherded the Patient Protection and Affordable Care Act through the Senate in 2010; and Lee Metcalf (served 1961 to 1978), a pioneer of the environmental movement.Montana's House district is the largest congressional district in the United States by population, with just over 1,023,000 constituents.It is the second largest House district by area, after Alaska's at-large congressional district.