Answer:
Most connections are on the East Coast.
"The United States has the largest rail transport network size of any country in the world. The nation's earliest railroads were built in the 1820s and 1830s, primarily in New England and the Mid-Atlantic region. The Baltimore and Ohio Railroad, chartered in 1827, was the nation's first common carrier railroad." per Wikiapedia.
Explanation:
https://en.wikipedia.org/wiki/Rail_transportation_in_the_United_States
