Comment by fragmede

Go to the union hall, sign up, pass a test, wait a lifetime (because there's a line of people ahead of you), get called in finally, start as an apprentice, work, do well, get put on the list as a trained apprentice, eventually get called into trained apprentice jobs, train up through the years, become a journeyman and later a master, all while cycling between working and waiting for work. If you're amicable, you can move up the list and get called more frequently because the person in control of the list can just do that, or alternately, someone at a job site can call for you specifically which will get you work faster than simply waiting around for work from the list.

There are still union trades in the US, but they're a dying breed.