NEW ORLEANS (AP) — Gulf Coast officials and residents marked the fourth anniversary of Hurricane Katrina with a mix of solemn remembrances and celebrations of how far the region has come in its recovery from the storm’s devastation.

In New Orleans, the day began with wreath-laying ceremonies and a traditional tolling of the bells to mark the time of the catastrophic levee breaches. A plaque also was unveiled at the New Orleans Katrina Memorial, where the remains of 84 unidentified or unclaimed victims are interred.

In Biloxi, the schedule included a prayer ceremony and sculpture unveiling on the town green, near the Gulf waters that wiped out much of that community.

‘‘All the destruction is hard to get over,’’ Mayor A.J. Holloway said this week. ‘‘But I think we’ve mastered that, and I think we’ve gone in a new direction. We like to say, we reach a milestone each and every day.’’

The death toll from Hurricane Katrina is estimated at more than 1,600 in Louisiana and Mississippi. Damage is estimated to be billions of dollars. Four years later, the progress that’s been made is unmistakable, seen in the continued return of residents — estimates put New Orleans’ population at 75 percent or more of its pre-Katrina level.

Infrastructure and institutions have been rebuilt, such as New Orleans’ long-dismal public school system. Festivals to acknowledge this were planned in areas including New Orleans and neighboring St. Bernard Parish, which was virtually wiped out by the storm.

But it’s still rare for a day to pass without Katrina appearing in a news story or coming up in casual conversation. Yellow-brown water lines stain some derelict homes, and vast swaths of some neighborhoods remain in ruins. Life here, for many, remains measured in terms of pre- and post-Katrina.

Tears pooled in the corners of Terrence Miranda’s eyes as the 61-year-old talked about the home that was swallowed by 8 feet of flood water in New Orleans’ Lakeview neighborhood. He’s since rebuilt.

Standing outside the gates of the Katrina memorial, he said that with each passing day, ‘‘it’s more important to celebrate our rebirth than to memorialize’’ Katrina. ‘‘That may be a little cold, but you have to move on.’’

That seemed to be the message, too, of Mayor Ray Nagin, who honored those lost but also thanked those who returned in spite of the uncertainties — and he exhorted them to press on.

‘‘You know, I just think back and wonder, How did we get here? And we got here through a lot of hard work and, most importantly, we got here through the grace of God,’’ he told dozens of people gathered under at the one-time cemetery for the city’s unclaimed, where the memorial stands. ‘‘Because if we weren’t a blessed people, we would not be here today, to do what we’re doing.’’

Nagin, who was re-elected to a second term months after the storm and is leading his final anniversary commemoration as mayor, said he had mixed emotions about the day.

But he said it was important to ‘‘acknowledge that we are on the road to full recovery and that if we keep doing what we’re doing, this city is going to be better. This region’s going to be better, and we’re going to have some of the things that we’ve always dreamed about.’’