Answer:
Immigrants were encouraged to vote in large numbers by political machines.
Step-by-step explanation:
Immigrants who are offered free rent, food, housing and medical support, and do not want to lose all these benefits, they will vote for the polital party that keeps handing all of these to them.
Also, immigrants were encouraged to vote in the northern cities. And if they want to vote in the US, they have to be legal citizens.
Good luck!