It was freezing on New Year’s Eve in Manhattan.

A fresh layer of snow blanketed the ground on the night of Dec. 31, 1967, and revelers in Times Square and Central Park seemed to look to the future with some hope. “World Bids Adieu to a Violent Year” was the Jan. 1 headline in The New York Times.

But 1968 would be tumultuous, too.

Even from the distance of a half-century, the moment feels familiar. From January to December, people demonstrated against racial injustice and economic inequality. Abroad, the United States military slogged through a seemingly interminable war. And after two terms with a Democrat in the White House, a Republican presidential candidate campaigned on a promise of law and order, and won.

It was the year between the Summer of Love and the summer of Woodstock, and some men grew their hair long while others were drafted to fight in Vietnam. “The country was bitterly divided: hawks and doves,” said Marc Leepson, an author, historian and Vietnam veteran.

Photo: Associated Press

It was also the year of the Tet offensive, an enormous attack by North Vietnamese forces, and of more than 16,000 American deaths in the Vietnam War, more than in any other year. Domestic support for the war effort faltered as antiwar protests exploded, most notably the riots at the Democratic National Convention in Chicago, to which the police responded with tear gas. Demonstrators, journalists and even some delegates were beaten and arrested.

Mr. Leepson spent almost all of 1968 serving at a base near the coastal city of Qui Nhon, Vietnam, and he returned home that December to a country that seemed vastly different from the one he had left.

“The enormity of everything, individually and cumulatively, didn’t hit me until I was in my parents’ living room in Hillside, N.J., watching year-end roundups on the news,” he said in a phone interview. (He eventually joined Vietnam Veterans Against the War and grew his hair past his shoulders.)

While Mr. Leepson was overseas, a different sort of battle had been brewing in the United States. The civil rights movement had been underway for years, achieving landmark federal laws and Supreme Court decisions that struck down legalized segregation and discrimination.

Photo: Associated Press

But vast inequality persisted, and on April 4, the movement lost a leader: The Rev. Dr. Martin Luther King Jr. was shot and killed in Memphis.

In the following days, protests and riots erupted in major cities across the country. Properties were destroyed, and dozens of people lost their lives.

“His death unleashed this feeling that we were suppressed,” Sharlene Sinegal-DeCuir, a civil rights historian and an assistant professor at Xavier University of Louisiana, said of Dr. King. “Minority groups in America felt that they could now release all that and show the majority: This is our pain, and we have been telling you this for years and years.”

That message seemed to fall on deaf ears, she added, and demonstrations calling for racial justice have never stopped. “Adults need to really have an open mind and listen to the younger generation, and to their grievances,” she said. “I think that was not done in 1968.”

Instead, political opinion seemed to swing the other way. It was a presidential election year, and in March, Lyndon B. Johnson, a Democrat, said he would not run for president again, adding that there was “division in the American house.”

Photo: Associated Press

As the year went on, candidates found that appeals to “law and order” were polling particularly well. Richard M. Nixon did it best, eking out a Republican victory in November against Hubert H. Humphrey, a Democrat. (George Wallace, a third-party candidate who supported segregation, won millions of votes and five states.)

That election brought the end of the Johnson administration and the so-called Warren Court — the period when the Supreme Court, under Chief Justice Earl Warren, presided over a series of liberal rulings, most notably the 1954 decision striking down segregation in public schools. (Earlier in 1968, Chief Justice Warren told Johnson that he would retire, wrongly hoping the president could appoint a replacement before the winner of the election, whom Chief Justice Warren thought might be Nixon, took office.)

“It’s just a tremendously important moment in Supreme Court history,” Mary L. Dudziak, an author, historian and professor of law at Emory University, said of 1968. “It’s the beginning of that turn away from this era of expansive liberalism.”

Photo: Associated Press

But the big-picture changes were hard to recognize at the time; all year, major events made headlines at a breakneck pace. In April, a gas leak caused a huge explosion in Richmond, Ind., killing dozens of people and destroying numerous buildings. In June, Senator Robert F. Kennedy, a presidential hopeful, was fatally shot at a campaign event in California. Abroad, France was shaken by widespread protests and general strikes. A brutal civil war was unfolding in Nigeria. Soviet troops invaded Czechoslovakia. And the death toll kept rising in Vietnam.

When 1968 came to a close, Time magazine highlighted some good news. For its Men of the Year, it chose three who had just returned from very far away: the Apollo 8 astronauts Frank Borman, James A. Lovell Jr. and William A. Anders, the first people to travel around the moon and back. The journey of half a million miles went smoothly, and the men splashed down in the Pacific Ocean before returning to Houston in December. “We had a wonderful trip,” Mr. Lovell said.

New Year’s Eve was two days later. It was drizzling when the ball dropped in Manhattan and 1969 began.