You posted this claim on other threads. Perhaps you are unaware that the railroad expansion was financed by BRITISH capital until around the Civil War. By then Greenbacks were part of the money supply plus new deposits of gold had increased gold stocks and the money supply. Without those serendipitous discoveries the economy would have continued the stagnation resulting from Jackson's refusal to recharter the Second Bank of the United States. That foolish action plunged the US into a twenty year depression.
Gold will never again by a monetary instrument. Anymore than sailing ships will carry freight across the seas. Both are obselete.
This is just one of the ways in which sail power is being revived. For nine years a team of naval architects in Copenhagen, Denmark, has been working on a completely new design: a 50,000-tonne cargo ship whose diesel engine will be augmented by a set of high-tech sails set on six masts. Canvas is definitely out. Aerofoils are in.