Bluebulb Projects' The Measure of Things presents:
6,100 is about 45 times the number of Union Stations in the United States
In other words, it's 45.20 times the count of Union Stations in the United States, and the count of Union Stations in the United States is 0.0221 times that amount.
(a.k.a. Union Terminal; a.k.a. Joint Station; a.k.a. Union Depot) (2016 figures)