One of the predominant long-term trends in American demography has been the steady rise in the portion of the population that lives in cities or nearby them. The percentage of the U.S. population living in metropolitan areas has risen from 56 percent in 1950 to 87 percent in 2015. The percentage living in large metropolitan areas (over a million residents) has nearly doubled to 57 percent. In addition to the growth in population, the geographic size of metropolitan areas has increased noticeably since 1950. For much of the 20th century, this was due to urban areas becoming more sprawled out. But a major reason for this geographic growth today is that as the urban cores of metropolitan areas have grown larger, they have attracted a rising number of commuters from nearby rural counties, in many cases causing the rural counties to become part of their metropolitan area.
Data is from the 1950 to 2010 Decennial Census, as well as the 2015 Census Population Estimates
The expansion of metropolitan areas into rural America
The widespread construction of interstates and highways after World War II made it much easier for workers to commute longer distances to job centers. At the same time, agricultural employment declined in nearly every rural U.S. county, while manufacturing jobs in most small towns also began to disappear by the 1980s. The result of these two trends has been that residents in most rural counties have grown more dependent on nearby cities for jobs. Counties get included in a metro area once a certain percentage of their working residents are commuting into a nearby city, rather than participating in the rural county’s economy. In many rural counties, as the map below shows, the proportion of workers commuting to a nearby city has risen above a quarter of all workers, causing counties to become part of another city’s metropolitan area.The Office of Management and Budget determined the 1960 to 2015 metropolitan area boundaries