What was a solution to scarce living/working space in cities during the industrial revolution?

Massive infrastructure plans where made to make new "apartment complexes"  that could house the massive amounts of people immigrating into the cities at the time. Also the sub-burbs where created in-order to house people outside the city so that it wouldn't be too crowded. 

They were constantly being overlooked as a people and were being controlled by people who weren't really native to their homeland.