A full 7 percent of children in the U.S. have either been adopted or are stepchildren, according to a new Census Bureau report. The adopted account for 2.3 percent of kids under 18, while 4.7 percent are stepchildren.

Adoption rates vary little by state, though Alaska leads with a 4.2 percent rate. The adoption rate is 2 percent in California, New Jersey, New York and Texas. But, by county, adoption rate ranges from less than 1.9 percent to as much as 17.8 percent.

Adopted children by county. (Census)

The distribution of stepchildren was roughly in line with divorce rates: the share of householder kids who were stepchildren were highest in the South (5.1 percent) and lowest in the Northeast (2.9 percent).

Arkansas was home to the largest share of stepchildren, at 6.7 percent. They account for 6.6 percent of kids in Oklahoma, 6.3 percent in Wyoming and 6.1 percent in West Virginia. Washington, D.C. had the lowest rate—1.8 percent—followed by Massachusetts, New Jersey, New York and Connecticut (2.3 percent to 2.8 percent).

Stepchildren by county. (Census)