Industrialization encouraged cities to grow by creating economic growth and job opportunities in them.
Industrialization means more industry and more industry means more factories and work places. Most newly established factories were in the cities, creating demand for factory labor. This created more jobs and demands for housing, thus establishing urban areas ( apartments and houses for workers ).
As industrialization created jobs, more and more families from rural areas moved into cities. Apart from housing, they needed daily facilities, such as schools, offices, recreational areas, churches etc. All this contributed to expanding the city's territory and its growth.