Chicago ? The abortion rate in the United States has fallen to its lowest level since 1974, the first full year after the U.S. Supreme Court legalized the procedure nationwide, new data show.

The annual rate has been falling steadily since 1981, paralleling a sharp decline in the number of abortion providers. Recent years also have seen an upsurge in legislation making it more difficult for women to access abortions and for doctors to perform them.

Thirty-five years after the landmark Roe vs. Wade decision, in which the Supreme Court said women have a constitutional right to terminate a pregnancy, states have enacted hundreds of laws requiring mandatory waiting periods, parental consent for minors, ultrasound imaging of the fetus and numerous other regulations.

According to the figures being published today, the abortion rate was 19.4 per 1,000 women age 15-44 in 2005, the last year for which information is available. At its peak in 1981, the rate was 29.3, up from 19.3 in 1974.