The history of the United States that began in 2016 is notable for a return to great power rivalry between the United States, China, and Russia. This period has been called the Second Cold War as well as part of a Second Gilded Age driven by increasing wealth inequality. It has also been described as the beginning of the Seventh Party System, due to recent shifts in demographics and voting patterns.

In 2016, China surpassed the United States as the world's largest economy when measured by purchasing power parity (PPP). In the 2016 U.S. presidential election, the Republican Party ticket of Donald Trump and Mike Pence, using a populist message, defeated Democratic Party ticket of Hillary Clinton and Tim Kaine. Barack Obama finished his presidency by completing a withdrawal of thousands of U.S. troops from Afghanistan and declassifying alleged significant Russian interference in the 2016 United States elections.

During his first presidency, which began in 2017, Trump enacted tax cuts, increased immigration restrictions, expanded the Mexico–United States border wall, and signed the National Defense Authorization Act for Fiscal Year 2020 establishing the United States Space Force. Trump promoted an "America First" foreign policy that included a trade war with China. In December 2019, Trump was impeached for his alleged role in a scandal involving the Russo-Ukrainian War, for which he was subsequently acquitted. In 2020, Trump oversaw the federal government response to the COVID-19 pandemic and subsequent recession as he ran for reelection against Obama's vice president Joe Biden. The Democratic ticket of Biden and Kamala Harris beat Trump and Pence in the 2020 presidential election. Trump, along with his supporters, made multiple attempts to overturn the presidential election with false claims of fraud, which culminated with the January 6, 2021, attack on the U.S. Capitol in an attempt to stop the peaceful transfer of power. The attack and Trump's involvement led to his second impeachment and acquittal.

The presidency of Joe Biden, which began in 2021, included major legislation such as the American Rescue Plan Act, Infrastructure Investment and Jobs Act, CHIPS and Science Act, and the Inflation Reduction Act. Biden's foreign policy oversaw the complete withdrawal of U.S. troops that ended the war in Afghanistan, leading to the Taliban retaking control from the collapsed Afghan government. Biden kept tariffs from Trump's trade war with China. Biden responded to the Russian invasion of Ukraine that began in 2022 by imposing sanctions on Russia and authorizing civilian and military aid to Ukraine. Biden strongly supported Israel's military efforts during the Gaza war that began in 2023 before adopting a ceasefire proposal at the end of his term. Biden abandoned his 2024 reelection campaign and endorsed Harris, who lost to the Republican ticket of Trump and JD Vance in the 2024 United States presidential election.

Trump began his second presidency by pardoning around 1,500 January 6 rioters, initiating mass layoffs of the federal workforce, signing the Laken Riley Act, and starting a trade war with Mexico and Canada while escalating the trade war with China. Trump's administration suspended the provision of intelligence and military aid to Ukraine, offered concessions to Russia, requested half of Ukraine's oil and minerals as payment for U.S. support, and said that Ukraine bore partial responsibility for the invasion. These moves have been criticized by most of the United States' allies and by many international organizations. Trump's broad and extensive use of executive orders has drawn numerous lawsuits challenging their legality.

Domestic politics

2016 presidential election

In 2016, following several cybersecurity incidents, the Obama administration formally accused Russia of engaging in a campaign to undermine the 2016 election, and the administration imposed sanctions on some Russian-linked people and organizations.

Several candidates ran for the Republican presidential nomination in the 2016 presidential election that was won by Donald Trump, who prominently questioned Obama's place of birth during Obama's first term. The Democratic Party had fewer potential candidates to choose from, and the campaign early on centered on Hillary Clinton, former Secretary of State, United States Senator from New York, and First Lady of the United States. A surprise challenger to Clinton appeared in 74-year-old Vermont Senator Bernie Sanders, a self-identified democratic socialist and the one of only two independents in the Senate. Despite attracting a large, enthusiastic following among mostly young voters, Sanders was unable to secure the nomination. When the primary season finished in the spring, Clinton secured the Democratic nomination. By the spring of 2016, most GOP candidates had dropped out of the running aside from Trump, Ted Cruz, and John Kasich. Cruz and Kasich ended their campaigns in May while Sanders conceded the Democratic nomination in July, endorsing the presumptive nominee Hillary Clinton.

The 2016 elections took place on November 8. Obama was term-limited in 2016 due to the 22nd Amendment. In June 2016, with the Democratic primaries nearly complete, Obama endorsed former secretary of state Hillary Clinton as his successor. However, according to Glenn Thrush of Politico, Obama had long supported Clinton as his preferred successor, and Obama dissuaded Vice President Biden from running against Clinton. Obama spoke in favor of Clinton at the 2016 Democratic National Convention, and he continued to campaign for Clinton and other Democrats in the months leading up to Election Day.

As the primaries gave way to the general election, Hillary Clinton faced numerous controversies over her tenure as Secretary of State, namely an email server scandal. Polls and surveys showed that both Clinton and Trump had an overall negative image among voters. Meanwhile, Donald Trump chose as his running mate Indiana Governor Mike Pence. Pence, a staunch conservative Christian, was seen as a way of winning over heartland conservatives, many of whom were Ted Cruz supporters wary of Trump's attitude on social issues. Clinton chose as her running mate Virginia Senator Tim Kaine, seen as a way of connecting with blue collar white voters, Trump's base of support.James W. Ceaser, Andrew E. Busch, et al. Defying the Odds: The 2016 Elections and American Politics (2017) During the general election, controversies over remarks Donald Trump had made over the years seen as demeaning to women emerged in the press, including a beauty pageant he had been a judge on in the 1990s where he had criticized the appearance of a contestant, as well as a leaked 2005 audio tape in which he made vulgar statements about the treatment of women. Hillary Clinton, however, continued to be embroiled in controversies of her own, the biggest being the revelation that she had used an unsecured private email server during her tenure as Secretary of State, leaving the possibility of having mismanaged or compromised classified documents. In addition, John Podesta, Clinton's campaign manager, had his private email account hacked, releasing over 20,000 campaign emails in October and November 2016 by WikiLeaks.Ceaser, 2017.

On Election Day, November 8, Trump carried 306 electoral votes against Clinton's 232. He made considerable inroads into the old Rust Belt, carrying states such as Michigan, Wisconsin and Pennsylvania that had been safe Democratic territory since 1988. However, Donald Trump did not win the popular vote. This was the fifth time in American history that the outcome of the Electoral College did not match the outcome of the popular vote, the others happening in 1824, 1876, 1888, and 2000. The GOP also retained control a majority in both the House of Representatives and the Senate, controlling all branches of government. Allegations of Russian interference on behalf of Trump's candidacy in the 2016 election caused controversy during and after the election.

Trump and Obama frequently communicated during the transition period, and Trump stated that he sought Obama's advice regarding presidential appointments. However, President-elect Trump also criticized some of Obama's actions, including Obama's refusal to veto a UN Resolution condemning Israel settlements. In his farewell address, Obama expressed concerns about a divisive political environment, economic inequality, and racism, but remained optimistic about the future. Obama left office with roughly 8,400 US soldiers remaining in Afghanistan.

First Trump administration

On January 20, 2017, Trump took the oath of office as the 45th US president in the face of large-scale demonstrations from protesters unhappy with the outcome of the election and of the incoming president. On his first day in office, he undertook a series of executive orders aimed at dismantling the Affordable Care Act and Trans-Pacific Partnership, and also moved to pass a temporary ban on refugees from several Middle Eastern states. This last action met with widespread criticism, and the 9th Circuit Court of Appeals dismissed it as unconstitutional. On June 26, the Supreme Court overturned the 9th Circuit's decision, ruling that part of President Trump's executive order is constitutional. One of Trump's major accomplishments was nominating Associate Justice Neil Gorsuch to the Supreme Court. On April 10, Gorsuch was sworn in. In 2018, President Trump nominated Brett Kavanaugh to replace the departing Associate Justice Anthony Kennedy. The nomination process soon became contentious after several women, most notably Palo Alto University psychology professor Christine Blasey Ford, accused Kavanaugh of past instances of sexual assault. After a series of hearings, the US Senate voted to confirm Kavanaugh despite the controversy.

In 2017, Robert Mueller was appointed as special counsel to investigate Russian's involvement in the 2016 election, including allegations of conspiracy or coordination between Trump's presidential campaign and Russia. The Mueller Report, released in 2019, concludes that Russia undertook a sustained social media campaign and cyberhacking operation to bolster the Trump campaign. The report did not reach a conclusion on allegations that the Trump campaign had colluded with Russia, but, according to Mueller, his investigation did not find evidence "sufficient to charge any member of the [Trump] campaign with taking part in a criminal conspiracy."