The Agricultural Revolution that started the Industrial Revolution caused people to move to the cities looking for work and the population to rise because there was more food. In 1700, the population of Britain was 5.5 million. By 1840, it was 16 million people! Due to increased population and poverty, working class families lived in small rooms. Employers built inexpensive, poorly built row housing called tenements to house their workers but also get more profit, further contributing to overcrowding.