What were some Problems with using steam engines on American railroads?

They would have been similar to those of operating in any very large continent: long distances from coal supplies (or wood for the earliest); climates not conducive to steam operation, such as extreme cold or aridity; mountainous terrain giving long, steep gradients and other more general problems to the railways anyway. Possibly too, in the more remote areas, shortage of readily-available, skilled labour to drive and more particularly, the local skills and equipment to maintain and repair the locomotives. As the railways became more established these problems could be overcome.