Carnegie and Frick (Henry not William) were long dead and gone before the feds started setting rail road rates. And the mills in Birmingham and the mills in Pittsburgh were owned by the same companies. Why would they conspire to limit the market for their own mills in the South?
The big fights over railroad rate fixing were in the late 1800’s. The National Grange among others was engaged in fights over that. And Carnegie himself had extensive railroad holdings. He stood to benefit either way.
Pittsburgh is a nice place, but it would not have become so opulently wealthy if the fix had not been in.
>> Why would they conspire to limit the market for their own mills in the South? <<
They wouldn’t, of course.
But let’s not allow rational economic analysis to intrude upon a good old-fashioned populist screed against the evil capitalists.
I thought it interesting that the 1860 democrat party platform featured making coast to coast railways a national interest:
4. Resolved, That one of the necessities of the age, in a military, commercial, and postal point of view, is speedy communications between the Atlantic and Pacific States; and the Democratic party pledge such Constitutional Government aid as will insure the construction of a Railroad to the Pacific coast, at the earliest practicable period.