Why did American railroad workers have their own series of Social Security numbers, and why did they have a retirement /social security plan separate from the rest of American workers?
–SMM
Because railroad retirement happened before social security.
So did Federal workers until 1983 or so, and so still are many other Government employees.
They get a gov’t pension, thus no Soc Sec. In the case of the Railway workers, they got a special version of Soc Sec.
Several links here might offer some insight and contrasting views.
Many other American workers are part of pension plans that exempt them from SS.