Thomas Edison patented the light bulb in 1879. This development quickly became common in homes as well as factories, transforming how even lower and middle-class Americans lived. Although slow to arrive in rural areas of the country, electric power became readily available in cities when the first commercial power plants began to open in 1882. When Nikola Tesla developed the alternating current system for the Westinghouse Electric & Manufacturing Company, power supplies for lights and other factory equipment could extend for miles from the power source. Alternating current power transformed the use of electricity, allowing urban centers to physically cover greater areas. In the factories, electric lights permitted operations to run twenty-four hours a day, seven days a week. This increase in production required additional workers, and this demand brought more people to cities.

Gradually, cities began to illuminate the streets with electric lamps to allow the city to remain alight throughout the night. No longer did the pace of life and economic activity slow substantially at sunset, the way it had in smaller towns. The cities, following the factories that drew people there, stayed open all the time.