In an effort to reduce these statistics, Congress is giving states a challenge: Reduce the out-of-wedlock birth rate and share in $100 million.
Now, four states and the District of Columbia have been notified by the Department of Health and Human Services that they are the first year's winners, provided they can prove that abortions also declined.
The winners were diverse, and officials were puzzled to explain their success. Massachusetts began with one of the lowest unwed birth rates; the District of Columbia had the highest, with a 65 percent of babies born to a single mother.
The winners had a variety of explanations for their success.
"There's been a message about welfare changing," said Joel Sanders, who directs Alabama's welfare reform program. He also credited the strong economy.
But he acknowledged that virtually every state has tough welfare rules and a strong economy.
In Massachusetts and California, officials credited programs that give communities money to create pregnancy prevention programs, generally focused on teen-agers.
"It's a combination of programs and changing social mores among families in California, where out-of-wedlock pregnancy is no longer as easily accepted," said Anna Ramirez, who runs California's Office of Family Planning.
The winners have until Sept. 1 to prove that abortions did not increase between 1995 and 1997. Those that do will share the $100 million. An additional $100 million will be awarded in each of the next several years, based on subsequent data.
The contest includes all births outside marriage to teens and adults, to families on and off welfare.
While many states have targeted teen-agers, teen-age moms account for only one in three unwed births.
And though states credit the welfare overhaul, the first bonuses were based on statistics from 1996 and 1997, when the changes were just beginning.
"It definitely can't just be from the welfare reform because of the timing. It has to be other things," said Stephanie Ventura, who tracks birth trends for the National Center for Health Statistics.
The unwed birth rate peaked in 1994 at 32.6 percent and has been relatively stable since then, after climbing dramatically through the late 1980s and early 1990s. In 1985, it was just 22 percent.
To reduce the out-of-wedlock rate, the number of illegitimate births must fall more quickly than births to married women. That's tricky, given that all births including marital births are dropping across the country, Ventura said.
The District of Columbia may have benefited from demographics. Births to unmarried black women have been dropping across the country, and the district's population is overwhelmingly black.
But no one is really sure what's going on.
"There is no question that the large fiancial bonus has created interest in the states and a lot of programs and policies large and small have been implemented," said Kristin Moore, who studies these issues at Child Trends. "But it probably was not in time to have caused these declines."