Final answer:
Cities in the southern and western US have grown due to economic opportunities, a favorable climate, affordable housing, and less crowding. The Sun Belt has become a permanent home for many, with the growth of the service industry and tech firms. Historical trends and current advances in technology have further facilitated this urbanization.
Step-by-step explanation:
The growth of southern and western cities in the United States can be attributed to various factors including economic opportunities, climatic preferences, and technological advancements. The migration trend towards the Sun Belt, defined by a quest for more favorable climate and lifestyle, has led to significant urbanization. The service industry and information technology boom, along with affordable housing and less crowding compared to areas like southern California, have made these regions attractive for relocation. The historical demographic shifts pushing for the occupation of the West were similarly motivated by the prospects of economic gain and political strategy, in times past ensuring the spread of "spreading freedom" was aligned with U.S. territorial expansion.
Moreover, cities in the Sun Belt have seen jobs created in high-tech firms and other tertiary sector industries, causing a sustained increase in population. Migration from both within the country and from northern states escaping harsh winters has turned what used to be a seasonal migration into a permanent growth trend. This movement has been driven significantly by the rise of new technologies and the service industry. Suburban growth has seen a major uplift in these regions with cities like Dallas-Fort Worth-Arlington in Texas becoming one of the fastest-growing metropolitan areas in the country according to a report by the US Census Bureau.