State and federal government generally saw unions as anti-capitalist and un-American. They often deployed the powers of the state against them, often with no real justification.
Examples of this physical power include:
President Hayes sending in federal troops with machine guns to end the Railroad Strike of 1877. This strike collapsed in the face of overwhelming force.
Similarly, in 1984, Cleveland sent in federal troops to end the Pullman Strike, an action which led to the deaths of 34 people in Chicago.
The US government also used laws to blatantly prosecute unions, e.g. the Sherman Anti-Trust Act from the 1890s onwards.
The Supreme Court also showed little inclination to side with unions over employers.
The Slaughterhouse Case of 1873 showed that the Court could not intervene in companies violating their rights, because it was a private practice.
‘Yellow Dog’ contracts were also deemed constitutional.