On November 27, 2015, a mass shooting occurred in a Planned Parenthood clinic in Colorado Springs, Colorado, resulting in the deaths of three people and injuries to nine. A police officer and two civilians were killed; five police officers and four civilians were injured. After a standoff that lasted five hours, police SWAT teams crashed armored vehicles into the lobby and the attacker surrendered.The attacker, Robert Lewis Dear Jr., was arrested, charged in state court with first-degree murder, and ordered held without bond. At court appearances, Dear repeatedly interrupted proceedings, made statements affirming his guilt (although he did not enter a formal plea), and expressed anti-abortion and anti-Planned Parenthood views, calling himself "a warrior for the babies." He also asserted his desire to act as his own attorney in the criminal case against him. Subsequent mental competency evaluations ordered by the state court determined Dear to be delusional. The judge presiding over the state case ruled in May 2016 that Dear was incompetent to stand trial and ordered him indefinitely confined to a Colorado state mental hospital, where he has remained ever since. In 2018, the court ruled that Dear remains incompetent to stand trial. In December 2019, separate federal charges were brought against Dear.

The incident drew comments from the anti-abortion and abortion-rights movements, as well as political leaders. This was the second of two shootings in Colorado Springs in less than a month; the first occurred 28 days earlier.

The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, 326 Indian reservations, and nine minor outlying islands. At nearly 3.8 million square miles (9.8 million square kilometers), it is the world's third- or fourth-largest country by geographic area. The United States shares land borders with Canada to the north and Mexico to the south as well as maritime borders with the Bahamas, Cuba, and Russia, among others. With a population of more than 331 million people, it is the third most populous country in the world. The national capital is Washington, D.C., and the most populous city and financial center is New York City.

Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago, and European colonization began in the 16th century. The United States emerged from the Thirteen British Colonies established along the East Coast. Disputes with Great Britain over taxation and political representation led to the American Revolutionary War (1775–1783), which established the nation's independence. In the late 18th century, the U.S. began expanding across North America, gradually obtaining new territories, sometimes through war, frequently displacing Native Americans, and admitting new states. This was strongly related to belief in manifest destiny, and by 1848, the United States spanned the continent from east to west. Slavery was legal in the southern United States until the second half of the 19th century, when the American Civil War led to its abolition. The Spanish–American War and World War I established the U.S. as a world power, and the aftermath of World War II left the United States and the Soviet Union as the world's two superpowers. During the Cold War, both sides fought in the Korean and Vietnam Wars but avoided direct military conflict. They competed in the Space Race, culminating in the 1969 American spaceflight that first landed humans on the Moon. The Soviet Union's dissolution in 1991 ended the Cold War, leaving the United States as the world's sole superpower.

The United States is a federal presidential-constitutional republic with three separate branches of government, including a bicameral legislature. It is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, NATO, and other international organizations. It is a permanent member of the United Nations Security Council. Considered a melting pot of cultures and ethnicities, its population has been profoundly shaped by centuries of immigration. The United States ranks high in international measures of economic freedom, quality of life, education, and human rights; it has low levels of perceived corruption. However, scholars have criticized it for racial, wealth, and income inequality, capital punishment and mass incarceration, and lack of universal health care.The United States is a highly developed country, and its economy accounts for approximately a quarter of global GDP and is the world's largest by GDP at market exchange rates. By value, the United States is the world's largest importer and second-largest exporter of goods. Although its population is only 4.2% of the world's total, it holds over 30% of the total wealth in the world, the largest share held by any country. Making up more than a third of global military spending, it is the foremost military power in the world and a leading political, cultural, and scientific force.