LOS ANGELES, CA - Los Angeles remains the nation's most populous county, with 10.17 million residents as of July 1, 2015, the U.S. Census Bureau reported today.

The figure represents a 3.6 percent increase from the 9.81 million residents in the county on April 1, 2010. According to the Census Bureau, 683,731 births were reported in the county during that five-year span, compared to 316,911 deaths.

Cook County, Illinois, the nation's second most populous county, has 5.2 million residents -- roughly half of the Los Angeles County population. In Orange County, the population rose 5.3 percent during the same five- year period, from 3.01 million as of April 1, 2010, to 3.16 million residents as of last July 1.

Neither Los Angeles nor Orange made the list of fastest-growing U.S. counties with at least 10,000 residents from 2014-15. The fast-growing county in the country during that period was McKenzie County, North Dakota, which saw its population grow from 10,995 residents in 2014 to 12,826 last year -- a 16.7 percent increase. In fact, the three fastest- growing counties from 2014-2015 were in North Dakota.