With the development of easy train travel and the building of highways and the popularization of the automobile in the 1940s and 1950s, Americans had an easier time traveling between destinations. The suburbs allowed people to live outside of cities, in less condensed areas, as well to be able to purchase affordable housing that still allowed them to commute into cities for the purpose of work. After the second World War, the growing population, as well as the inexpensive land in the sunbelt region, the lack of union involvement in industry, and warmer climate, encouraged millions of Americans to move away from the Northern states and for companies to begin to relocate their businesses and factories to the Southern and South Western states.