Thousands of pro-life activists will descend on the US capital Tuesday in protest on the 40th anniversary of a landmark US Supreme Court ruling guaranteeing abortion rights under the Constitution.
This year's March for Life will take place three days later, on Friday, due to festivities surrounding President Barack Obama's inauguration to a second term on Monday.
Meanwhile the pro-choice movement, advocating for abortion rights, will organize local meetings, diners and conferences to mark the anniversary of the January 22, 1973 "Roe v. Wade" ruling.
The delicate question over whether a woman has the right to choose to terminate a pregnancy -- and thus, critics argue, end a life -- has long caused deep and bitter divisions in the very fabric of American society, and triggered several deadly incidents.
Polls lay bare the stark divide between the pro-life and pro-choice camps.
A Pew poll showed that more than six out of 10 Americans would not like to see the high court overturn Roe v. Wade, against 29 percent who would like to see it struck down -- opinions that have not shifted much since surveys conducted 10 and 20 years ago.
In May, Gallup said there had never been so few pro-choice supporters -- at 41 percent, against 56 percent in 1995 -- while 50 percent said they were pro-life, compared to 33 percent 16 years ago.
A flurry of abortion-related laws have nonetheless been passed at the state level, usually advanced by the powerful pro-life lobby and fought by the pro-choicers.
The Guttmacher Institute on sexual and reproductive health counted a record number of 92 abortion-related laws passed in 2011, and 43 in 2012.
They range across a wide spectrum, from measures limiting late-stage abortions to barring health care insurance reimbursements for the operation and a requirement for the pregnant woman to get a sonogram.
About 1,800 clinics provide abortion services today across the United States, but 83 percent of counties do not have such centers. There is only one clinic in Mississippi, a southern state with three million inhabitants.
And just four doctors offer controversial late-term procedures, as the Supreme Court ruling legalizing abortion also granted states the right to limit the procedure in the final trimester of a pregnancy.
Although late-term procedures make up just one percent of all abortions in the United States, they are the most controversial, facing particularly virulent protests by abortion opponents.
In one of the most violent incidents, physician George Tiller, a prominent practitioner of late-term abortions, was shot dead by an extremist in 2009.