As individuals aspired to live closer to their manufacturing jobs, towns and cities expanded during and after the Industrial Revolution. People frequently lived in tight quarters in order to be closer to their employment. These employment were generally low-paying, but they were not seasonal like agricultural labour. In addition to proximity to work, other factors such as transportation cost, safety, and cultural attractions led people to move to cities. Cities provided a social environment where people could meet others who had similar interests, which was important for advancement in a new industry. They also had government offices that people could go to with questions or problems, and police departments that could help if someone was being threatened or attacked. Cities also had large markets full of stores where one could find everything from food to clothing to entertainment. All in all, cities were attractive places to live because they offered opportunities that rural areas did not. During the 19th century, when agriculture became more industrialized, city populations increased even more. By 1920, half of all Americans lived in cities, and by 1975 this number was expected to rise to two thirds. Cities are important for economic development because they provide industries that need large quantities of products and services from small businesses. They also provide workers for larger companies. A city's economy is dependent on how successful these efforts are at attracting people to live there and keep them coming back for more.