NEW YORK — By today’s politically polarized standards, the Supreme Court’s momentous Roe v. Wade ruling was a landslide. By a 7-to-2 vote on Jan. 22, 1973, the justices established a nationwide right to abortion.
Forty years and about 55 million abortions later, however, the ruling’s legacy is the opposite of consensus. Abortion ranks as one of the most divisive issues in the country, and is likely to remain so as rival camps see little space for common ground.
Unfolding events in two states illustrate the divide.
In New York, a bastion of liberal abortion laws, Governor Andrew Cuomo pledged in his Jan. 9 State of the State speech to entrench those rights even more firmly. In Mississippi, where many antiabortion laws have been enacted in recent years, the lone remaining abortion clinic is on the verge of closure because nearby hospitals won’t grant obligatory admitting privileges to its doctors.
‘‘Unlike a lot of other issues in the culture wars, this is the one in which both sides really regard themselves as civil rights activists, trying to expand the frontiers of human freedom,’’ said Jon Shields, a professor of government at Claremont McKenna College.
On another hot-button social issue — same-sex marriage — there’s been a strong trend of increasing support in recent years, encompassing nearly all major demographic categories.
There’s been no such shift, in either direction, on abortion.
For example, a new Pew Research Center poll finds 63 percent of US adults opposed to overturning Roe, compared with 60 percent in 1992. The latest Gallup poll shows 52 percent of Americans saying abortion should be legal under certain circumstances, 25 percent wanting it legal in all cases, and 20 percent wanting it outlawed.
‘‘There’s a large share of Americans for whom this is not a black-and-white issue,’’ said Michael Dimock, the Pew center’s director.
Many conflicted respondents tell pollsters they support the right to legal abortion while considering it morally wrong.
Backers of legal access to abortion were relieved that President Obama defeated Mitt Romney in November.
The Supreme Court justices are believed to divide 5 to 4 in favor of a broad right to abortion. Romney, if elected, might have been able to appoint conservative justices who could help overturn Roe v. Wade, but Obama’s victory makes that unlikely at least for the next four years.
Abortion-rights groups also were heartened by a backlash to certain antiabortion initiatives and rhetoric.
In Missouri and Illinois, Republican candidates for the US Senate lost races that their party initially expected to win after making widely criticized comments regarding abortion rights for rape victims who become pregnant. In Virginia, protests prompted GOP politicians to scale back a bill that would have required women seeking abortions to undergo a transvaginal ultrasound.
‘‘All these things got Americans angry and got them to realize just how extreme the other side is,’’ said Jennifer Dalven, director of the American Civil Liberties Union’s Reproductive Freedom Project.
However, antiabortion leaders see cause for optimism.
In the past two years, after Republican election gains in 2010, GOP-dominated state legislatures have passed more than 130 bills intended to reduce access to abortion. The measures include mandatory counseling,ultrasound for women seeking abortions, bans on abortion after 20 weeks of pregnancy, and curbs on how insurers cover the procedure.
The ACLU and other abortion-rights groups are challenging several of the laws in court, notably the 20-week ban.