SAN JOSE — As the deadline requiring a Real ID to fly domestically arrived Wednesday, airport lines across the Bay Area largely remained at standard lengths.

Beginning Wednesday, travelers were expected to bring a REAL ID-compliant state driver’s license or identification card for domestic air travel, no longer using a standard driver’s license or ID card some 20 years after Congress passed the Real ID law in the wake of the Sept. 11, 2001, terrorist attacks.

Many observers had worried aloud that the change in requirements might lead to chaos and long lines Wednesday, but there was little evidence of it at Bay Area airports and few reports of trouble nationwide.

“My only worry is for the people that don’t have one, that don’t realize today’s the day and maybe they’ll get delayed,” said Pat O’Connor, 55, a resident of Virginia who was visiting his son at Stanford. “It could cause longer waits, but I’ve given myself plenty of time.”

The deadline’s arrival has caused Bay Area DMV locations to be flooded in recent weeks as people scramble to get a compliant ID, with many residents waiting for hours outside to submit their required documents. As of May 1, about 58% of driver’s license and ID cardholders in California had upgraded to a Real ID, said Chris Orrock, information officer for the California Department of Motor Vehicles.

Travelers do have alternative options if they have not yet been able to get a Real ID. Passports and tribal identification can be used to travel domestically, and those without a Real ID will still be allowed to fly but will be subject to additional security screening steps, Secretary of Homeland Security Kristi Noem announced earlier this week.

But traveling without a Real ID can still lead individual travelers to experience delays, airport officials warned.

“Passengers who present a state-issued identification that is not Real ID-compliant and who do not have another acceptable form of photo identification can expect to face delays, additional screening and the possibility of not being permitted into the security checkpoint, if their identity cannot be verified,” said Kaley Skantz, spokesperson for Oakland International Airport. “For individuals who have not yet obtained a Real ID-compliant identification, we recommend arriving early to accommodate additional screening measures at the checkpoint.”

To prepare for the new requirements, San Jose Mineta International Airport and the Transportation Security Administration added additional staff to help at security checkpoints and assist travelers who do not yet have a Real ID, said Ana Maria State, assistant public information manager for SJC. On Wednesday morning, there were no long lines or delays.

At the Oakland International Airport, there were “no significant backups” Wednesday, Skantz said.

On Wednesday at SJC, travelers pulled their carry-on suitcases past signs proclaiming the need for a Real ID as they joined mild security lines and approached the TSA checkpoint. For many SJC travelers, the new requirement did not impact their travel plans.

Titus Britt, a 61-year-old resident of Sunnyvale, got his Real ID ahead of the first deadline when he moved between cities, a process that he said was not very different from getting his driver’s license. But for Seraphine Britt, 57, who got hers four years ago, the process was “hectic” and required going back home to get different documents twice and returning to the DMV, she said.

But the Britts did still plan an extra 30 minutes into their travel day in case of longer security lines, Titus Britt said.

“Some other people might not have it yet, which could cause delays for us,” he said.

Garin Aravaci, 27, of Santa Clara said that he did not think ahead about potential delays from the new requirement but added that he got his Real ID when he moved from Florida — an easy process, he said.

Yolie Burrows, a resident of Gilroy, had been planning to fly with her sister to Idaho to help her daughter move back to the Bay Area, she said. But her sister does not have a Real ID or a passport, so that plan has been upended.

“She’s not going to be able to do it,” Burrows said. “She’s going to start the process, but I don’t think she’s going to be able to get it.”

Burrows has had her Real ID — which was “a process” to get because it required her birth certificate and other documents — so she did not build extra time into her travel day beyond what she normally would, Burrows said.