Big and Small America : U.S. Most Populous Counties 2016
March 30,
2018 by Jane Chero in General 
Big and Small America is a term coined by the Census Bureau to reflect the present geographical spread of the American population. Over 50 percent of residents live in just 143 counties (Big America) with the remaining 50 percent spread out over a vast area encompassing 2,999 additional counties (Small America). This is the first factoid in a series of four factoids detailing the migration of residents to populous cities.
This migration is in part due to more workers seeking jobs in large cities as manufacturing jobs have left the U.S. Along with greater job opportunities, the lure of warmer climates has drawn Americans to the southern and western states. The most growth has been seen in regional hub areas and coastal areas with ports. Southern and Western areas along with larger cities have also been impacted by Immigration.
50 percent of the population lives in 4.6 percent of counties – roughly 161.7 million residents. These Big American counties average, 485,846 in population. Medium sized counties average 211,321 persons and house 10.7 percent of the nation. Very small U.S. counties totaling 2,664 represent 84.8 percent of counties and the remaining 25 percent of the population. Small counties average only 20,402 in population.
Also surprising is that over 10 percent of the population resides in just seven counties, three of which are in California. By far, Los Angeles County is the nation’s most populous with over 10 million residents in 2016. With just half the size (5.2 million), Cook County, IL has the second highest population, followed by Harris County, TX, Maricopa County, AZ, San Diego County, CA, Orange County, CA, and Miami-Dade, FL.
Source: U.S. Census Bureau, 2016 Population Estimates