About 300 flights went through Logan by about 6 p.m. Saturday, with roughly 100 more expected that evening -- all told, about a quarter of the 1,200 to 1,300 that come in and out on average Saturday.

With the reopening, Reagan National Airport at Washington remained the only major U.S. airport still closed to travel. Federal authorities said its proximity to the Pentagon and other federal buildings created enough security concern to keep it closed for now.

At Logan, many travelers did not seem to mind the added restrictions, the long waits or the presence of U.S. marshals, the Border Patrol and officers in black SWAT uniforms. A sign told passengers that once past security checkpoints, they could be subject to random searches and ID checks.

"They need to do what they need to do to make it safe," said Joe Carnation, 64, of Santa Rosa, Calif.

On Tuesday, hijackers -- boarding flights in Boston, Newark, N.J., and Washington -- crashed two airliners into the World Trade Center, one into the Pentagon, and a fourth into the Pennsylvania countryside.

Investigators are trying to determine how the 10 terrorists armed with knives were able to board two flights at Logan, take over the airliners, and fly them into the World Trade Center.

Limited air travel resumed across the country Thursday and slowly increased on Friday and Saturday. The government also reopened the skies to most private planes, though they remained banned from flying within about 30 miles of Washington and New York City.

"At a time like this, who could complain about having to wait in line?" said Christina Bond, a resident of Walnut Creek, Calif., who was at the airport in San Jose, Calif.

Massport officials say passengers should not expect a quick return to normal operations, and they should plan for delays due to increased security.

"The traveling public knows -- and needs -- to expect a slow methodical start-up to our aviation system," Massport Director of Aviation Thomas Kinton said Friday.

Logan Airport was the last to open among the three airports where planes took off Tuesday and were hijacked. Washington-Dulles International Airport and Newark International Airport reopened Thursday.

There were a few bumps in an otherwise smooth reopening. An unruly passenger was removed from a Delta flight Saturday morning, and a Northwest flight to Minneapolis Saturday evening was delayed after three unruly passengers forced officials to deplane passengers.

Also, Worcester Regional Airport closed Saturday morning after an employee noticed an open door on a Delta plane. Officials closed the airport for about four hours while state police bomb squads swept the plane. The passengers were bused to Manchester, and the airport reopened around 1:15 p.m.

At Logan on Saturday, Dr. Amai Elan of Jerusalem spotted a police Rottweiler and said, "There's something we have not seen for years (in Boston)."

Elan, who flies frequently, said the new measures are just starting to approach the tougher standards he has long seen overseas.

"In Heathrow, you can see people with submachine guns all the time," he said. "They look vigorous -- strong people with bulletproof vests."

In large part because many Americans are too scared to fly, Continental, Northwest and American said they are cutting back their schedules by 20 percent. Continental, the nation's fifth-largest airline, also said it is furloughing 12,000 employees -- more than one-fifth of its work force.

In Phoenix, America West announced it will no longer serve meals to save time and money.

Some terminals at New York's Kennedy Airport -- which along with the metropolitan area's two major airports reopened Friday -- looked like ghost towns, with restaurants shut down and only an occasional taxi passing outside. Others were mobbed with travelers, some of whom had spent days sleeping on cots and eating out of vending machines.

One group of travelers, a group of high school students visiting Lasell College from Puerto Ordaz, Venezuela, said they had been worried about safety, but heard about the increased security and decided to fly.

"There's a lot of dogs and policemen," said Maria de los Angeles. "I feel comfortable."