This report from the Alan Guttmacher institute shows that in 2011, there were only 16.9 abortions per 1000 women aged 15-44. That's the lowest rate since 1973, and represents an annual drop of 4-5% since 2008, for a 13% drop overall. Guttmacher attributes the drop to the increased uptake of contraception, particularly among younger women, and to a shift toward use of long-acting reversible forms of contraception such as the IUD, injections and sub-dermal implants. These are much more effective than shorter-term chemical contraceptive methods such as the pill, patches or vaginal rings.
The most controversial part of the report has been its assertion that it could attribute little of the decline to the recent spate of anti-abortion laws passed by various states. This is partly because many of the laws passed too recently to have taken effect by the 2011 year they were measuring. Some of the laws simply added more information to already-existing counseling requirements; these seemed to have had no effect. Some limited or banned late-term abortions, but these would do little to reduce abortion numbers, because only 1.2% of abortions occur after week 20 of gestation. Guttmacher does concede that some state laws (like those requiring abortion facilities to meet requirements similar to surgical centers, or requiring all abortion providers to have hospital admitting privileges) may have interrupted the availability of abortion services, reducing the number of abortions; and that other laws (e.g., law requiring an additional in-person counseling session 24 hours in advance of the abortion) might have made it more difficult for women to seek abortion. Louisiana passed restrictions on clinics and experienced a 19% decline; Missouri imposed the extra counseling visit and experienced a 21% decline. But it's hard to tell how much of the impact was due to legal restriction. While the new restrictive laws were concentrated in the Midwest and the South, the number of clinics actually only fell in the Northeast and the West. And there is little overall correlation of laws to abortion-rate decline. Rates fell most dramatically in the Midwest (17%), but below the national rate-of-decline in the South (12%). The West experienced a 15% decline and the Northeast a modest 9%. Pro-choice states California, New Jersey and New York experienced 16%, 12% and 9% declines respectively, in the complete absence of new restrictive laws.