Antiabortion activists stage a "die-in" in front of the White House on Jan. 28. Buoyed by conservative gains in the November midterm election, the antiabortion movement is mobilizing on behalf of bills in Congress and several state legislatures that would further curtail women's access to the procedure. (Pablo Martinez Monsivais/Associated Press)

Abortion in America is an extremely divisive issue, splitting Republicans and Democrats with often very strong feelings.

It also divides the states. In 2010, according to a new study from the Guttmacher Institute, an abortion rights group, an estimated 11 percent of all unintended pregnancies in South Dakota were aborted. In New York, it was 54 percent.

In general, Guttmacher's numbers show that states with more people who oppose abortion rights tend to have lower abortion rates. But views on abortion tend to have much less impact on something else related to all this: unintended pregnancies.

In fact, some of the states that oppose abortion the most also have some of the highest rates of unintended pregnancies -- particularly in the South. And on average, the states that favor abortion rights the most have slightly lower levels of unintended pregnancies.

The chart below ranks the 10 states with the highest and lowest percentages of abortion opponents (per the Pew Research Center's 2007 Religious Landscape Survey), compared to where those states rank as far as having the fewest unintended pregnancies (according to data compiled by Guttmacher from the federal Pregnancy Risk Assessment Monitoring System and similar state programs, along with regression models).

These numbers include all states -- plus the District of Columbia -- except Alaska, Hawaii and Wyoming, for which reliable polling data is harder to come by.

State Most abortion opponents Fewest unintended pregnancies
Mississippi 1 48
Utah 2 1
Kentucky 3 15
West Virginia 4 26
Arkansas 5 37
North Dakota 6 7
Louisiana 7 46
South Dakota 8 11
Tennessee 9 42
Alabama 10 38
New Jersey 39 32
Rhode Island 40 30
California 41 19
Maryland 42 44
New York 43 41
New Hampshire 44 6
Connecticut 45 25
Vermont 46 14
Massachusetts 47 16
Maine 48 17

On average in the 10 states that oppose abortion the most, 51 percent of pregnancies are unintended. In the top 10 states that most favor abortion rights, it's 50 percent.

Here's how much each state supports abortion rights, per Pew.

(Scroll over the map for state-by-state data.)

And here's the percentage of unintended pregnancies that were aborted in 2010 in each of those states, per Guttmacher.

These two charts match up very closely, as noted above, because more abortion-rights opponents tends to mean fewer abortions. Women in many of the more antiabortion states often have less access to abortion (i.e. fewer clinics nearby) and might have to clear more regulatory hurdles, such as having an ultrasound before the procedure.

But now notice how different the map below -- which shows the percentage of pregnancies that were unintended -- is from the two above. Suddenly, there is no clear red-blue delineation. It's much more regional.

Your eyes are immediately drawn to the South, of course. That's where most of the states with the highest rates of unintended pregnancy are located. In fact, five Southern states that rank in the top 10 for opposing abortion rights also rank in the top 11 for most unintended pregnancies.

Mississippi, for instance, is the state that opposes abortion rights the most, according to Pew, with 64 percent generally opposing the procedure. It is also the state with the most unintended pregnancies, at 62 percent of all pregnancies, according to Guttmacher. After accounting for fetal loss, about two-thirds of those unintended pregnancies were brought to term.

By contrast, Massachusetts is one of the most pro-abortion-rights states, with just 28 percent of people opposing the procedure. But it's also on the low end as far as the percentage of unintended pregnancies (44 percent). Far fewer -- 43 percent -- of those pregnancies were brought to term.

So although Massachusetts had more than twice as many people as Mississippi in 2010, Mississippi had significantly more unintended pregnancies brought to term (14,000 vs. 11,000 for Massachusetts) -- both by virtue of its rate of unintended pregnancy and its opposition to abortion.

Correction: The year of the Pew study is 2007, not 2013. The post has been fixed. 

Scott Clement contributed to this post.