Obviously the poor had no money, so the bosses of say New York would pay clueless immigrants to vote for them in elections to keep them in high city offices and to continue holding power.
State Representation is based off the population of the state, since slaves weren't technically citizens, they were not counted in deciding how many representatives a state had. Slaves were a large majority of the population in the south. The south thought they were under represented and wanted slaves to be counted so representation was fair in their eyes.
Location is Rome if I am correct