New York: A settlement located on the Genesee River had become Rochester, N.Y. the largest flour-producing city in the world and had rightfully earned the nickname: "the Flour City."
Birmingham, AL: was and still is rich in iron, lime stone and coal which brought about its steel industry. This city took form in 1871 and was pioneered by the Elyton Land Company. There are no major rivers in Birmingham which was the reason why railroads were constructed here to shift these rich deposits which were ultimately turned into steel. During the years 1871 to 1873, this city (then a small mining industrial town), Also nicknamed "The Magic City."
You could mention Pawtucket, Rhode Island where Slater built his famous textile mills that brought the Industrial Revolution to the U.S.
Pittsburgh was a big one because it was the steel capitol