The history of the lands that became the United States began with the arrival of the first people in the Americas. These indigenous cultures would eventually form numerous societies, each with their own distinct traditions and ways of life. Their arrival marked the beginning of human presence in what would later become the United States.

On July 4, 1776, the thirteen British colonies declared their independence from the Kingdom of Great Britain, forming the United States of America. This declaration, written primarily by Thomas Jefferson, was a foundational document in the American Revolution and established the principles of liberty and democracy that would define the new nation.

Following the American Revolution, the Articles of Confederation proved inadequate for governing the new nation. In response, the Philadelphia Convention drafted a new Constitution in 1787, which was ratified by the necessary number of states by June 21, 1788. This Constitution established the framework for the federal government and has been the cornerstone of U.S. law ever since.

The Civil War was a pivotal conflict fought between the Union (the northern states) and the Confederacy (the southern states) over issues including slavery and states' rights. The war resulted in the defeat of the Confederacy, the abolition of slavery, and a more centralized federal government. The war marked a significant turning point in U.S. history, leading to the Reconstruction era and the extension of legal and voting rights to freed male slaves.

The Great Depression, triggered by the Wall Street Crash of 1929, was a decade-long economic downturn that severely impacted the United States. President Franklin D. Roosevelt's New Deal policies aimed to alleviate the suffering. The U.S. entry into World War II in 1941, following the Japanese attack on Pearl Harbor, marked a significant shift in global politics and cemented the U.S. as a world power. The war effort also spurred industrial growth and technological advancements.

The Civil Rights Movement was a period of significant social change, marked by protests, marches, and legislative actions aimed at ending racial segregation and discrimination. Key events included the Montgomery Bus Boycott, the March on Washington, and the passage of the Civil Rights Act of 1964 and the Voting Rights Act of 1965. These efforts were led by figures such as Martin Luther King Jr. and resulted in substantial advancements in civil rights for African Americans.

The collapse of the Soviet Union in 1991 marked the end of the Cold War, leading to a new era of international relations. This period also saw the rise of globalization, with increased international trade, technological advancements, and the emergence of the U.S. as the world's sole superpower. The U.S. continued to play a dominant role in global affairs, including involvement in various international conflicts and economic initiatives.

On September 11, 2001, terrorist attacks on the World Trade Center in New York City and the Pentagon in Washington, D.C. resulted in significant loss of life and a profound impact on U.S. foreign policy and national security. The attacks led to the War on Terror, including the wars in Afghanistan and Iraq, and a heightened focus on homeland security.

The election of Barack Obama as the first African American President of the United States marked a historic milestone in American history. His presidency was notable for several key policies, including the Affordable Care Act (Obamacare) and efforts to address climate change and economic recovery following the 2008 financial crisis.

The COVID-19 pandemic, which began in late 2019 and peaked in 2020, had a profound impact on the United States, causing widespread illness, economic disruption, and changes in social behavior. The same year saw a highly contested presidential election between incumbent President Donald Trump and challenger Joe Biden, with Biden ultimately winning the presidency. This period highlighted the resilience of the American people and the adaptability of the U.S. healthcare and political systems in the face of unprecedented challenges.