US opposition to communism as a menace to capitalism, democracy, and freedom spread in the wake of Russia's Communist Revolution (1917).

Official anticommunism endured. In the Red Scare (1917–20), the Justice Department monitored, raided, and arrested thousands of communist, socialist, antiwar, civil rights, and labor activists. Red-baiting during the Depression, New Deal, and Cold War (1945–89) was abetted by white and black conservatives, liberals, and leftists, including politicians, journalists, academics, and unionists. Congressman Martin Dies (D–TX) and Senator Joseph McCarthy (R–WI) chaired infamous anticommunist committees. Meantime, FBI witch-hunts targeted federal departments, the army, and civil rights organizations.