Which of the following statements, best summarizes the system of railroads shown on the map?
The railroads established by 1860 each began, and ended at a major American city or port
The majority of the railroads that connected the north to the south were built by 1850
The primary direction of the railroads built between 1850 and 1860 was north to south
The extent of the railroads in the south was very limited compared to that of the north