The Pew Forum has this summary of the results of their 2007 survey on abortion views. There is a strong correlation between religious identification and the position held. The most support for legal abortion comes from those who identify as Jews. The least support comes from Jehovah's Witnesses. Even stronger is the correlation between practice and position, with 61% of those who attend services weekly opposing abortion.

Overall, U.S. citizens polled at 18% favoring legal aborion in all cases, 35% legal in most cases, 24% illegal in most cases, and 16% illegal in all cases.

For those of us on the Pro-Life side, the most heartening statistic is that less than 1 in 5 Americans favors completely unrestricted legal aborion, and 3 out of 4 favor some restriction.