When Joe Biden was sworn in as the 46th president of the United States today, it was a moment of political triumph that had been decades in the making. His long career in public office spanned eight presidents, from Richard Nixon to Barack Obama, but the nation’s highest office always eluded him. Now, Biden, 78, finally joins their ranks.

The story begins with an Irish Catholic family in northeastern Pennsylvania. Biden was born in 1942, the eldest son of Joseph Robinette Biden Sr. and Catherine Eugenia Finnegan Biden. He was also a son of Scranton, Pennsylvania, which would become central to his political identity. The Biden family moved to Delaware when he was 10 years old.

>> PHOTOS: Scenes from the inauguration of Joe Biden and Kamala Harris in Washington, D.C.

After graduating from law school, Biden got his start in local politics in Delaware, winning an election to the New Castle County Council in 1970. Two years later, at just 29 years old, he challenged a well-known Republican incumbent, Sen. J. Caleb Boggs, a former Delaware governor. Biden won in a major upset.

Weeks after Biden’s victory, his wife, Neilia, and their 13-month-old daughter, Naomi, were killed in a car accident. Biden considered giving up the Senate seat that he had just won, but was persuaded to serve. He was sworn in at the hospital where his sons were treated for injuries from the crash.

As a senator, Biden commuted to Washington by train, a routine that allowed him to return home to his children each night. In the 1970s, he was a vocal opponent of busing, and decades later, he would come under fire after recalling working with segregationist senators during his early years in the Senate. As time went on, he gained clout in the chamber, becoming the top Democrat on the Judiciary Committee and then the panel’s chairman.

In 1987, Biden began his first presidential campaign, aiming to win the Democratic nomination the following year. The 44-year-old candidate presented himself as representing a new generation and declared, “We must rekindle the fire of idealism in this country.” But his bid was derailed by a plagiarism scandal, and he dropped out of the race months before the first nominating contest.

His presidential hopes dashed, Biden faced a far graver kind of peril in early 1988: a life-threatening brain aneurysm that required emergency surgery. Not long after that, he had another operation for a second brain aneurysm. Later that year, he returned to the Senate after a seven-month absence.

As chairman of the Senate Judiciary Committee, Biden presided over confirmation hearings for six Supreme Court nominees, including Robert Bork, whose nomination Biden succeeded in defeating, and Clarence Thomas. The memory of the Thomas hearings would linger for decades as Biden faced criticism for his handling of Anita Hill’s testimony before his committee.

Biden also left his mark on consequential legislation, playing a leading role in passing the 1994 crime bill, which would become associated with mass incarceration. The Violence Against Women Act, one of Biden’s top legislative achievements, became law as part of the crime bill.

Biden immersed himself in foreign policy during his decades as a senator, rising to serve as chairman of the Senate Foreign Relations Committee. In 2002, he voted to authorize the war in Iraq, a vote that he later called a mistake.

Two decades after his first presidential bid imploded, Biden decided to try again in the 2008 election. Now in his 60s, he ran as a leader steeped in foreign policy, but he stumbled immediately when he described a rival candidate, Obama, as “the first mainstream African American who is articulate and bright and clean and a nice-looking guy.” Biden’s campaign never caught on with voters, and he dropped out after finishing in a distant fifth place in the Iowa caucuses.

After Obama won the Democratic presidential nomination in 2008, he selected Biden to be his running mate. The choice added a dose of foreign policy experience to the ticket and began a close political partnership between the two men. As vice president, Biden oversaw the implementation of the 2009 stimulus bill and later headed the administration’s cancer moonshot program.

A skilled retail politician, Biden is known for his tactile, backslapping style, embracing one-on-one interactions on the campaign trail and elsewhere. His touchy-feely nature came under scrutiny in the #MeToo era, with a number of women saying he had touched them in ways that made them feel uncomfortable.

Decades after losing his first wife and daughter, Biden faced another family tragedy in 2015: His son Beau, who followed him into politics and served two terms as Delaware’s attorney general, died of brain cancer at 46. Biden cited his son’s death, and the grieving that followed, when he announced he would not run for president in 2016.

After leaving office as vice president, he published a memoir and gave paid speeches, earning millions of dollars. He campaigned for Democratic candidates before the 2018 midterm elections.

In the first months of 2019, the Democratic presidential field grew larger and larger, and Biden showed no urgency to declare his candidacy. He finally jumped into the race in late April, denouncing President Donald Trump as a threat to the nation’s character.

Despite his stature as a former vice president, Biden struggled to attract some primary voters who were turned off by his moderate brand of politics and his septuagenarian status — a far cry from his days as the 29-year-old Senate candidate. Biden fell flat in the first nominating contests, finishing in fourth place in Iowa and fifth place in New Hampshire.

Despite his early struggles in two overwhelmingly white states, Biden counted on receiving strong support from Black voters in later contests. A big win in South Carolina turned his campaign around, and after picking up a series of key endorsements from former primary rivals, he defeated a more progressive rival, Sen. Bernie Sanders of Vermont, to win the Democratic nomination.

The coronavirus pandemic upended the presidential race, and Biden limited himself to campaigning virtually for much of the spring as the outbreak raged. He eventually began making occasional in-person appearances, and in August, he chose one of his primary rivals, Sen. Kamala Harris of California, as his running mate.

Biden confronted an extraordinary general election that played out as the pandemic continued to disrupt American life. He repeatedly condemned Trump’s handling of the crisis, while the president and his allies tried to portray Biden as a tool of the far left.

The first general election debate quickly devolved into a headache-inducing brawl, as Trump repeatedly interrupted his opponent. Just days after sharing the stage with Biden, the president announced that he had tested positive for the coronavirus.

In his visits to battleground states, Biden held carefully arranged events with mask wearing and social distancing. Eschewing the packed events with big crowds that are a staple of presidential campaigns, he held a string of drive-in car rallies where voters beeped their horns to cheer him on.

Election night stretched deep into the week as ballots were counted in key states. Four days after polls closed, Biden was declared the winner. In the weeks that followed, Biden rolled out a diverse slate of Cabinet picks and prepared to take office.

Biden received the COVID-19 vaccine and promised to step up vaccinations across the country, setting a goal of getting 100 million shots into the arms of Americans in his first 100 days in office.

Early January brought a major boost to his hopes of passing his legislative agenda. Democrats won both runoff elections for Georgia’s Senate seats, putting their party in control of the chamber.

Biden’s inauguration Wednesday took place 48 years after he first arrived in Washington as one of the youngest people to be elected senator. With his swearing-in, he became the oldest president in American history.

© 2021 The New York Times Company