Could it be that the institutional racism of Jim Crow occurred not despite the Progressive era but because of it? Not only did the Progressive reforms create new economic rents that could be exploited by whites and by the politicians who enacted those reforms, but many leading Progressives espoused views on racial purity and segregation that put them in the vanguard of the American apartheid system.
The authors continue –
Robert Higgs ( 2008) writes that despite racist views by whites and despite the residual interracial violence and discrimination that existed after the Civil War, black Americans made significant economic and social gains. Many of those gains, however, occurred before the onslaught of Progressive economic regulation and the imposition of Jim Crow.Thus, one cannot claim that the institutionalized racism that came with progressivism simply was based on residual racism that existed after the war, as though the racial attitudes of that time inevitably would end in Jim Crow.  2008. Competition and Coercion: Blacks in the American Economy, 1865–1914. Cambridge, U.K.: Cambridge University Press.]
The Davis-Bacon Act is a pro-union law that discriminates against non-unionized black construction contractors and black workers. In fact, that was the original intent of the Davis-Bacon Act of 1931. During its 1931 legislative debate, quite a few congressmen expressed their racist intentions, such as Rep. Clayton Allgood, D-Ala., who said, “Reference has been made to a contractor from Alabama who went to New York with bootleg labor. This is a fact. That contractor has cheap colored labor that he transports, and he puts them in cabins, and it is labor of that sort that is in competition with white labor throughout the country.”