Image via flickr/Bill Dickinson.

After an eight-year run as the county with the biggest population gains in the U.S., Harris County, home to Houston, has relinquished the top spot to Maricopa County, home to Phoenix, according to new Census data released Thursday.

Between July 2015 and July 2016, Harris County added 56,587 people -- roughly 155 people per day -- while Maricopa County added 81,360 people -- around 222 people per day.

The shift is largely due to folks moving out of Harris County. Approximately 16,000 more people moved away from Harris County to another county than moved into it during that time period. But because of both natural increases and international migration, Harris County only slipped by one spot and still ranks second in population growth in the country. Article continues after graph.

The change likely reflects the local economy's performance relative to other cities and the lingering impact of the oil slump.

In 2015 and 2016, oil and gas-related layoffs in the Houston area hit roughly 81,000, according to new revised data from the U.S. Labor Department cited by the Houston Chronicle.

Looking at gains by metropolitan area, Houston still ranks second. It's above Phoenix, which ranks third, but the Dallas metro tops the list for biggest population gains during the period.