Jeff Katz is executive director of Listening to Parents, a national organization designed to eliminate barriers that prevent children in foster care from being adopted.

Why is it easier for an American family to adopt a child from across the world than adopt a foster child across a state line? State Department data show that in fiscal 2010, Americans adopted 11,058 children from other countries. By contrast, according to data from the National Data Archive on Child Abuse and Neglect, Americans adopted just 527 children from foster care across state lines that same year.

To lend perspective, according to the National Weather Service, twice as many Americans are struck by lightning each year.

The primary reason it is so hard to adopt across state lines is that the United States does not have a national adoption system. Instead, there is a different system in each state, the District of Columbia and Puerto Rico. Each jurisdiction has its own criteria for adoption eligibility and process for recruitment, approval and training of adoptive families.

Worse, our multitude of systems has created profound disincentives for states to allow residents to adopt children from other states. If, for example, a Maryland family adopts a Virginia child, Maryland has essentially wasted thousands of dollars to recruit and prepare a family, with no benefit to any Maryland child. In return, Maryland will receive a child who may well have expensive medical and educational needs. Meanwhile, Virginia is likely to receive a bonus of as much as $8,000 for placing the child in an adoptive family. Maryland will get nothing.

Since interstate adoption effectively has a “winner” (the state that sends the child) and a “loser” (the state that receives the child), states tend to hoard their families, greatly limiting matches for children and families across jurisdictions.

Ironically, this is particularly true when a family is interested in adopting the children who are hardest to place. If, for example, a family in Indiana is interested in adopting a large sibling group, the temptation is strong for Indiana to keep them waiting, in case an in-state group were to become available, instead of matching them immediately with children just over the border, say, in Chicago. This issue is particularly significant in large metropolitan areas that straddle state lines, such as New York, Philadelphia and Washington.

A group of child welfare experts who have studied programs nationwide for many years has identified a number of barriers that slow or prevent children from being adopted, including those that inhibit interstate adoption. Our forthcoming “No Barriers” report recommends common-sense and inexpensive ways to eliminate these issues, such as standardizing the certification process so that adoption home studies are accepted in all 50 states (just like your driver’s license) and changing federal funding programs so that both states share the benefit in an interstate adoption.

Finding parents to adopt children is not the problem. Far more people want to adopt children from foster care than there are children available. Data from the most recent National Survey of Family Growth, released in 2008, indicated that almost 600,000 women in the United States were actively trying to adopt. Most would adopt older children, minorities or sibling groups, the very children in foster care that need families and are considered “hard to place.”

Removing disincentives to interstate adoption could dramatically increase the number of children in foster care who become part of loving families. In 1997 Congress passed, with bipartisan support, the Adoption and Safe Families Act, which included strong financial incentives for states to increase the number of adoptions for their kids in foster care. Within three years, the number of children annually adopted from foster care doubled, from 25,000 to 50,000.

It has remained at that level for a decade. Incentives work.

There are more than 100,000 children in foster care waiting to be adopted. These children have been abused or neglected. They have no family and move from foster home to foster home, often carrying all their worldly possessions in a garbage bag. Fewer than half of these children will be adopted this year. The rest will grow another year older as they wait, wondering why no one wants them.

The shame is that thousands of willing parents do want them. But they are unable to adopt because of unnecessary barriers. If children can cross oceans to be adopted in the United States, surely they can cross state lines.