Mainly because slaves would find a way to escape and use the trains as a getaway. also it was easier to bring more and more slaves from the south to all of the other states. there are many different reasons you just have to find out what you think the answer is. if this is a question that you have to type then put a lot of the reasons. if this is a multiple choice see which one makes more sense and if that doesn't work try asking your teacher for help. they are there for a reason. not at all trying to be rude but I am struggling in school and am pretty much playing catch up so I have to use this site a lot.