Which of the following statements best summarizes the system of railroads shown in the map?
1. The majority of the railroads that are connected the North to the south were build by 1850
2. The railroads established by 1860 each began and ended at a major american city or port
3. The primary direction of the railroads built between 1850 and 1860 was north to south
4. The extent of the railroads in the south was very limited compared to that of the North