The union, like most other United States construction unions, had remained nearly all-white for most of its history. That began to change in the early 1960s, as the American civil rights movement began to challenge employment discrimination in the north, then picked up steam in the 1970s as the federal government began using the Civil Rights Act of 1964 to knock down some of the barriers to African-American workers' entry into the industry. Some local unions of the Iron Workers fought integration and affirmative action tenaciously, but usually unsuccessfully.