An estimated 17.3 million Americans move across county borders within the U.S. each year.

Survey figures compiled by the Census Bureau provide a glimpse of where these residents are moving to and from. The migration estimates are now readily available after the agency launched its Census Flows Mapper tool on Tuesday, allowing researchers to query migration data for each county.

Governing also previously reported on state to state migration patterns (view an interactive map).

Some of the most populous California counties were shown to have the top number of movers between counties, as compiled from survey data:

County of Residence 1 Year Ago Current County Annual Movers Margin of Error
Los Angeles, CA San Bernardino, CA 44,020 +/- 2,509
Los Angeles, CA Orange, CA 40,643 +/- 2,140
Los Angeles, CA Riverside, CA 30,443 +/- 2,486
Orange, CA Los Angeles, CA 28,450 +/- 2,015
Miami-Dade, FL Broward, FL 25,246 +/- 2,121
San Bernardino, CA Riverside, CA 23,942 +/- 2,017
Orange, CA Riverside, CA 23,663 +/- 2,325
Maricopa, AZ Pinal, AZ 21,969 +/- 1,659
Wayne, MI Oakland, MI 21,919 +/- 1,795
Cook, IL DuPage, IL 21,835 +/- 1,849
San Bernardino, CA Los Angeles, CA 20,921 +/- 1,592

The Census Bureau compiled the county-to-county migration flow estimates from American Community Survey data collected between 2005 and 2009, with published figures essentially representing annual averages over the time period.

Most often, people move relatively short distances. Separate census estimates indicated about 64 percent of moves in 2012 occurred within the same county.

By analyzing a larger sample over five years, the agency is able to compute estimates for all counties. But even with five years of data, some smaller counties still have high margins of error.

If you’re interested in learning more about how these figures were compiled, please refer to the Census Bureau’s documentation.