Pro-choice and pro-life demonstrators during the 2004 Washington, DC March for Women's Lives protest. Source: Declan McCullagh Photography, www.mccullagh.org (accessed Apr. 1, 2010)
The debate over whether or not abortion should be a legal option continues to divide Americans long after the US Supreme Court's 7-2 decision on Roe v. Wade  declared the procedure a "fundamental right" on Jan. 22, 1973.
Proponents, identifying themselves as pro-choice, contend that choosing abortion is a right that should not be limited by governmental or religious authority, and which outweighs any right claimed for an embryo or fetus. They say that pregnant women will resort to unsafe illegal abortions if there is no legal option.
Opponents, identifying themselves as pro-life, contend that individual human life begins at fertilization, and therefore abortion is the immoral killing of an innocent human being. They say abortion inflicts suffering on the unborn child, and that it is unfair to allow abortion when couples who cannot biologically conceive are waiting to adopt.
Variations exist in arguments on both sides of the debate. Some pro-choice proponents believe abortion should only be used as a last resort, while others advocate unrestricted access to abortion services under any circumstance. Pro-life positions range from opposing abortion under any circumstance to accepting it for situations of rape, incest, or when a woman's life is at risk. Pro-Choice and Pro-Life Groups
Some prominent pro-choice organizations include Planned Parenthood, NARAL Pro-Choice America, the National Abortion Federation, the American Civil Liberties Union (ACLU), and the National Organization for Women. Although many pro-life positions derive from religious ideology, several mainstream faith groups support the pro-choice movement, such as the United Methodist Church, United Church of Christ, the Episcopal Church, Presbyterian Church (USA), and the Unitarian Universalist Association. The 2016 Democratic Party Platform endorsed the pro-choice position, stating, "We believe unequivocally, like the majority of Americans, that every woman should have access to quality reproductive health care services, including safe and legal abortion - regardless of where she lives, how much money she makes, or how she is insured. We believe that reproductive health is core to women's, men's, and young people's health and wellbeing."  However, 26% of Democrats consider themselves to be pro-life. 
Some prominent pro-life organizations include The National Right to Life Committee, Pro-Life Action League, Operation Rescue, the Catholic Church, the Eastern Orthodox Church, Americans United for Life, the National Association of Evangelicals, Family Research Council, Christian Coalition of America, and the Church of Jesus Christ of Latter-Day Saints (Mormon Church).  The 2016 Republican Party Platform opposed abortion, stating, "We oppose the use of public funds to perform or promote abortion or to fund organizations, like Planned Parenthood, so long as they provide or refer for elective abortions or sell fetal body parts rather than provide healthcare... We will not fund or subsidize healthcare that includes abortion coverage... We thank and encourage providers of counseling, medical services, and adoption assistance for empowering women experiencing an unintended pregnancy to choose life."  However, 36% of Republicans consider themselves to be pro-choice. 
(click to enlarge image)
Bob Englehart's 1981 political cartoon "When Does Life Begin?," originally published by The Hartford Courant. Source: "Cartoon Plagiarism Case Offers a Metaphor for the Abortion Debate," www.ideagrove.com, Nov. 15, 2005
A 2018 Marist Poll and Knights of Columbus survey found that 51% of Americans consider themselves to be pro-choice, and 44% consider themselves to be pro-life. 
A 2017 Pew Research survey found that 57% of Americans say abortion should be legal in all or most cases, while 40% say it should be illegal in all or most cases. 
Pew Research found that 69% of Americans - 84% of Democrats and 53% of Republicans - surveyed said "No, do not overturn" in response to the question "Would you like to see the Supreme Court completely overturn its Roe versus Wade decision, or not?" 
A 2018 PPRI poll found that 45% of women and 42% of men agreed abortions should be covered by most health insurance plans. 
Surgical abortion (aka suction curettage or vacuum curettage) is the most common type of abortion procedure. It involves using a suction device to remove the contents of a pregnant woman's uterus. Surgical abortion performed later in pregnancy (after 12-16 weeks) is called D&E (dilation and evacuation).  The second most common abortion procedure, a medical abortion (aka an "abortion pill"), involves taking medications, usually mifepristone and misoprostol (aka RU-486), within the first seven to nine weeks of pregnancy to induce an abortion.  The Centers for Disease Control and Prevention (CDC) found that 67% of abortions performed in 2014 were performed at or less than eight weeks' gestation, and 91.5% were performed at or less than 13 weeks' gestation.  77.3% were performed by surgical procedure, while 22.6% were medical abortions.  An abortion can cost from $500 to over $1,000 depending on where it is performed and how long into the pregnancy it is. 
Abortion techniques were developed as early as 1550 BC, when the Egyptian medical text Ebers Papyrus suggested that the vaginal insertion of plant fiber covered with honey and crushed dates could induce an abortion. Abortion was an accepted practice in ancient Greece and Rome. Greek philosopher Aristotle (384–322 B.C) wrote that "when couples have children in excess, let abortion be procured before sense and life have begun..."  In the latter days of the Roman Empire, abortion was considered not as homicide but as a crime against a husband who would be deprived of a potential child. 
Throughout much of Western history, abortion was not considered a criminal act as long as it was performed before "quickening" (the first detectable movement of the fetus, which can occur between 13-25 weeks of pregnancy).  American states derived their initial abortion statutes from British common law, which followed this principle.  Until at least the early-1800s, abortion procedures and methods were legal and openly advertised throughout the United States.  Abortion was unregulated, however, and often unsafe. 
In 1821, Connecticut became the first state to criminalize abortion. The state banned the selling of an abortion-inducing poison to women, but it did not punish the women who took the poison. Legal consequences for women began in 1845 when New York criminalized a woman's participation in her abortion, whether it took place before or after quickening.  In the mid-1800s, early pro-life advocate Dr. Horatio Robinson Storer (1830-1922) convinced the American Medical Association to join him in campaigning for the outlawing of abortion nationwide.  By the early 1900s, most states had banned abortion. By
(click to enlarge image)
Demonstrators holding pro-choice and pro-life signs. Source: "New Pew Poll Shows Support for Legal Abortion Drops to Lowest Level in 15 Years," LifeNews.com, Apr. 29, 2009
1965, all 50 states had outlawed abortion, with some exceptions varying by state. 
The motivation behind these early abortion laws has been disputed. Some writers argue that the laws were not aimed at preserving the lives of unborn children, but rather were intended to protect women from unsafe abortion procedures , or to allow the medical profession to take over responsibility for women's health from untrained practitioners.  Others say that pro-life concerns were in fact already prevalent and were a major influence behind the efforts to ban abortion. 
Roe v. Wade
Federal action on abortion didn't occur until Roe v. Wade, which declared most state anti-abortion laws unconstitutional. The high court's 7-2 decision established rules based on a pregnancy trimester framework, banning legislative interference in the first trimester of pregnancy (0-12 weeks), allowing states to regulate abortion during the second trimester (weeks 13-28) "in ways that are reasonably related to maternal health," and allowing a state to "regulate, and even proscribe" abortion during the third trimester (weeks 29-40) "in promoting its interest in the potentiality of human life," unless an abortion is required to preserve the life or health of the mother.  The decision also allowed states to prohibit abortions performed by anyone who is not a state-licensed physician. 
The initial Roe v. Wade lawsuit was filed at the Dallas federal district courthouse on Mar. 3, 1970 by pregnant Texas resident Norma McCorvey, named in court documents as "Jane Roe." Henry Wade, Dallas County District Attorney from 1951 to 1987, was the named defendant. McCorvey was seeking to end her pregnancy, but abortion was illegal in Texas except to save the mother's life.  McCorvey said the pregnancy was the result of rape, but she later retracted that claim, admitting she lied in the hope of increasing her chances of procuring an abortion. The baby was eventually delivered and given up for adoption.  McCorvey later abandoned her support of abortion rights, becoming a pro-life activist and an evangelical Christian in 1995. She then converted to Catholicism and took part in silent prayer vigils outside abortion clinics. 
Immediately following Roe v. Wade, pro-life proponents pushed for federal legislation that would restrict abortion. In 1976, Congress passed the appropriations bill for the Departments of Labor, Health, Education, and Welfare (now the Department of Health and Human Services) which included an amendment ending Medicaid funding for abortions. Known as the "Hyde Amendment," this provision banning federal funding for abortions has been renewed with various revisions every year since its inception.
At the Aug. 1984 United Nations International Conference on Population held in Mexico City, Mexico, President Ronald Reagan announced the Mexico City Policy,  which restricted all non-governmental organizations funded by the US Agency for International Development (USAID) from performing or promoting abortion services. President Bill Clinton rescinded the policy (Jan. 22, 1993); President George W. Bush reenacted it (Jan. 22, 2001); President Barack Obama again rescinded it (Jan. 23, 2009); and President Donald Trump again reinstated it (Jan. 23, 2017).  
(click to enlarge image)
A coat-hanger is a frequently used symbol for abortion rights. Source: "Celebrating 25 Years of Decriminalized Abortion in Canada, gender-focus.com, Jan. 26, 2013
On June 29, 1992 the US Supreme Court case Planned Parenthood of Southeastern Pennsylvania v. Casey  (5-4) upheld the constitutional right to have an abortion, but it abandoned the "rigid trimester framework" outlined in Roe v. Wade and adopted a less restrictive standard for state regulations. The decision allowed states to impose waiting periods before a woman can obtain an abortion, allowed some legislative interference in the first trimester in the interests' of a woman's health, and permitted parental consent requirements for minors seeking abortions.  The Court ruled that none of these conditions imposed an "undue burden" upon women seeking abortions, but some pro-choice advocates warned that Roe v. Wade had been significantly weakened and that states would limit abortion access. 
On Nov. 5, 2003, after passing in the US House of Representatives (281-142) and the US Senate (64-34), the Partial-Birth Abortion Ban Act of 2003  was signed into law by President George W. Bush. This federal legislation banned physicians from providing intact dilation and extraction (aka "partial-birth" abortion), a late-term (after 21 weeks gestation) method which accounted for 0.17% of abortion procedures in 2000.  The act defines a "partial-birth abortion" as "an abortion in which the provider deliberately and intentionally vaginally delivers a living fetus until... the entire fetal head is outside the body of the mother, or... any part of the fetal trunk past the navel is outside the body of the mother, for the purpose of performing an overt act that the person knows will kill the partially delivered living fetus." Pro-choice advocates challenged the constitutionality of the Partial-Birth Abortion Ban Act of 2003; however, the Apr. 18, 2007 US Supreme Court case Gonzales v. Carhart/Gonzales v. Planned Parenthood  upheld the act, ruling 5-4 that it did not impose "an undue burden on a woman's right to abortion."
The topic of abortion was raised during the 2009-2010 US Congress health care debate. Some pro-life advocates said the Patient Protection and Affordable Care Act would allow federal funding for abortions, a claim denied by abortion rights supporters. To ensure passage of the bill, President Obama signed an executive order "to establish an adequate enforcement mechanism to ensure that Federal funds are not used for abortion services," re-affirming Hyde Amendment restrictions and extending them to cover the newly created health insurance exchanges. 
In Mar. 2017, the Department of Health and Human Services announced that all federally-funded shelters housing undocumented unaccompanied minors are henceforth prohibited from taking "any action that facilitates" access to abortion.  The American Civil Liberties Union (ACLU) challenged this decision in Garza v. Hargan, and on Mar. 30, 2018 the US District Court for the District of Columbia issued an injunction, ruling that the federal government must not interfere or obstruct any "unaccompanied immigrant minor children who are or will be in the legal custody of the federal government" from having an abortion while the case is being heard. 
State restrictions on abortion access increased sharply after the 2010 midterm elections, in which Republicans gained at least 675 state legislative seats, the biggest gain made by any party in state legislatures since 1938.  Between 2011 and 2017, states enacted over 400 new abortion restrictions.  These represent 34% of the 1,193 restrictions enacted since Roe vs. Wade in 1973.  Between Jan. and Mar. 2018, 308 new abortion restrictions were introduced in 37 states, 10 of which were enacted (in Idaho, Indiana, Mississippi, South Dakota, and Utah). 
(click to enlarge image)
Anti-abortion sign and wooden crosses placed outside the Whole Woman's Health abortion provider in McAllen, TX. Source: "Anti-Abortion Groups Push New Round of Abortion Rules in Texas," nytimes.com, Nov. 22, 2012
On Apr. 13, 2010, Nebraska's Republican Governor Dave Heineman signed a law banning abortions at or after 20 weeks of gestation on the theory that a fetus can feel pain by that time. The law was the first in the United States to restrict abortions based on fetal pain.  After Nebraska's law was passed, several other states enacted similar laws.  On Mar. 6, 2013, Idaho's fetal pain law was the first to be struck down by a federal court.  As of June 2018, 17 states have fetal pain laws on their statute books. 
On Apr. 27, 2010, the Oklahoma legislature signed a law requiring pregnant women seeking an abortion to undergo an ultrasound and listen to a detailed description of the fetus's heart, limbs, and organs. While other states had passed laws requiring women to undergo an ultrasound before having an abortion, Oklahoma's law was the first that required women to watch the monitor and listen to a detailed description of the fetus.  However, the law was struck down by the Supreme Court in 2013.  As of June 2018, 26 states have laws regulating the provision of ultrasound by abortion providers; three of these states (LA, TX, WI) require the abortion provider to display and describe the image to the pregnant woman. 
On Mar. 29, 2011, Arizona became the first state to criminalize abortions based on the sex or race of a fetus. The bill, signed into law by Republican Governor Jan Brewer, was opposed by Democrats, who said there was little evidence that sex- or race-selection abortions were taking place in the state.  As of June 2018, eight states (AZ, AR, KS, NC, ND, OK, PA, SD) ban sex-selection abortions; Arizona is the sole state to ban race-selection abortions. 
North Dakota is the only state to ban abortions in cases of fetal abnormality; enacted in 2013, the law prohibits abortion even when the fetus will die before or shortly after birth. 
In Mar. 2013, North Dakota outlawed abortions as early as six weeks after a woman's last menstrual period, when a fetal heartbeat can first be detected.  A federal appeals court struck down the law in 2015, noting that the law "violates Supreme Court precedent establishing that abortion is legal until a fetus is viable outside of the womb, usually about 24 weeks into pregnancy."  In 2018, the governors of Mississippi and Iowa signed into law similarly restrictive abortion laws banning abortion at 15-weeks and 6-weeks respectively; both laws have been put on hold by federal judges pending appeals. 
Despite an 11-hour filibuster from State Senator Wendy Davis, the Texas legislature passed a law in 2013 that added new restrictions to the state's abortion regulations. It required doctors performing abortions to have admitting privileges in local hospitals and required abortion clinics to have the same building standards as ambulatory surgical centers. The number of clinics providing abortion services fell from 42 to 19 over the next two years. On June 27, 2016, the US Supreme Court struck down the Texas law. Writing for the majority, Justice Stephen Breyer said: "neither of these provisions offers medical benefits sufficient to justify the burdens upon access that each imposes… each violates the Federal Constitution."  A similar 2015 law in Arkansas, which required abortion providers using pills to induce abortion in the first nine weeks of pregnancy (medication abortions) to have admitting privileges at local hospitals, was initially blocked by a federal judge in 2016 citing the Texas case.  A Federal Court of Appeals overturned this decision in 2017, and in 2018 the Supreme Court refused to hear a challenge to the law, resulting in Arkansas being the first state to ban medication abortions; further appeals are expected. 
From Roe v. Wade through 2017, over 60 million legal abortions were estimated to have been performed in the United States – an average of about 1.4 million abortions per year.  In 2014, 19% of pregnancies (excluding miscarriages) ended in abortion, and 1.5% of women aged 15-44 had an abortion.  At 2014 abortion rates, one in twenty US women will have an abortion before age 20, one in five by 30, and about one in four by 45.  11% of women having an abortion are teenagers, while most women having abortions are in their 20s: 32% aged 20-24 and 27% aged 25-29. 
The US abortion rate fell 29% between 1990 and 2005, from 27.4 to 19.4 abortions per 1,000 women of childbearing age, before leveling out from 2005-2008.  Between 2008 and 2011, the abortion rate dropped again by 13% to its lowest point since 1973: 17 abortions for every 1,000 women; in 2014 the rate dropped another 14% to 15 abortions per 1,000 women.  Pro-choice supporters credited an increased use of new birth control methods such as Mirena (an intra-uterine device that can last for several years) as one of the reasons for the decline. Pro-life groups credited an increase in anti-abortion laws at the state level amongst other factors, although abortion rates dropped faster than the national average in some states that had not enacted abortion restrictions, such as Illinois, where the rate dropped by 18%. 
The number of abortion providers has been declining since 1984, after it reached a peak of 2,908 providers in 1982.  There were 1,671 abortion providers in the United States in 2014, including 272 abortion clinics, 516 non-specialized clinics, 638 hospitals, and 245 physicians' offices.  90% of US counties did not provide abortion services, with 39% of women living in those counties.  Between 2011 and 2017, at least 126 clinics providing abortion services closed.  Seven states (KY, MO, MS, ND, SD, WV, WY) have only one clinic left.  Pro-choice advocates believe increased clinic violence has contributed to this downward trend in abortion providers.  In 2016, 6% of abortion clinics reported losing staff members as a result of anti-abortion violence or harassment.  According to the National Abortion Federation, a professional association of abortion practitioners, at least 229 arson attacks/bombings were committed against abortion providers between 1977 and 2017, with at least another 99 attempted arson attacks/bombings.  Additionally, at least 11 abortion providers were murdered during that time and there were at least 26 attempted murders of clinic staff and physicians.  Mainstream pro-life leaders and organizations have publicly denounced violence committed against abortion providers and clinics.