In America, ... the anti-union Taft–Hartley Act ... outlawed actions taken by unionized workers in support of workers at other companies, effectively rendering both solidarity actions and the general strike itself illegal.

So, a general strike is illegal in the USA.

But, remember the history of unions. The Luddites were textile workers who were upset that the mill and factory owners were breaking the law and denying their rights. With the government ignoring their rights and the owners trampling over them, the Luddites prepared to fight:

The Luddites met at night on the moors surrounding industrial towns to practice military-like drills and manoeuvres.

Then they broke things:

They wrecked specific types of machinery that posed a threat to the particular industrial interests in each region

And they killed:

Four Luddites, led by a man named George Mellor, ambushed and assassinated mill owner William Horsfall of Ottiwells Mill in Marsden, West Yorkshire, at Crosland Moor in Huddersfield.

And the government killed them:

The harsh sentences of those found guilty, which included execution and penal transportation, quickly ended the movement.[5][35] Parliament made "machine breaking" (i.e. industrial sabotage) a capital crime with the Destruction of Stocking Frames, etc. Act 1812

The point is, trade unions were a compromise. Get rid of trade unions and what you get instead is mob violence against factory owners. People die.

"Meet our demands or we're going to walk around outside holding signs instead of working."

vs.

"Meet our demands or we're kill you and destroy your equipment."

If a general strike is illegal, then why stop at a strike? "In for a penny, in for a pound."