This Granite Railway, or Quincy Railway, was built to a 5 foot gauge in 1826. The US railway evolution would certainly have been different if coal had been more important during the 1700's. But, a few railways were started, of varying gauges - each serving a mine or quarry and to a dock, as in Great Britain. The second railway in the US was a mining railway, planned in the mid-1700's, a gravity railway for the mining at Mauch Chunk, Pennsylvania, and built in 1827. More energetic ideas for railways were moving along though, with innovative thinkers in Maryland, South Carolina, and Massachusetts moving forward with railways.
Rapid growth is an understatement.
Within only two years, the US was in the railroad business at a tremendous rate. Within a few more years, railroads were scattered thoughout the US, and of varying gauges, of course. As the growth continued, the potential for a major east-west railroad was being discussed. Several routes were planned, and many arguments were heard, and tensions grew between the North and the South. By the time the Pacific Railway Act was passed in 1862, it was obvious that the North exerted more pressure.