Traveling during the Christmas season can be hectic under normal circumstances, but a higher terrorism alert in the United States could mean an even more difficult time for travelers.

The nation Sunday moved to an “orange” terrorism alert — the second-highest level of alert. It is the fifth time the alert has reached orange but the first during the Christmas holidays.

South Carolinians are taking precautions in response. Officials at the Columbia Metropolitan Airport and at the State Ports Authority have increased security.

The Bush administration appealed to Americans not to abandon plans to travel, even if airports presented more of a hassle because of increased vehicle and baggage searches, police with bomb-sniffing dogs and parking restrictions.

“Our government is doing everything we can to protect our country,” President Bush said Monday. “American citizens need to go about their lives, but as they do so, they need to know that governments at all levels are working as hard as we possibly can to protect the American citizens.”

Other precautions likely will include increases in the number of air marshals, particularly on flights arriving from overseas, and undercover surveillance around airports, said Brian Jenkins, research associate at the Mineta Transportation Institute at San Jose State University and a special adviser to the Rand Corp.

Federal officials would not discuss details of their planning.

Cargo planes and flights originating overseas were of special concern. Officials say steps have been taken to improve security in both areas, but some critics call for the screening of all packages on cargo planes to prevent smuggling of bombs.

Most travelers appeared to take safety restrictions in stride, several airport officials said.

“I’m always impressed with passengers’ ability to respect security concerns. The mood is very supportive,” said Fred Szabo, commissioner of Cleveland Hopkins International Airport.

In South Carolina, police and hospitals already have maintained high levels of disaster readiness.

State Law Enforcement Division Chief Robert Stewart reviewed the new security alert in a conference call with Homeland Security Secretary Tom Ridge on Sunday.

“There’s nothing specific to South Carolina,” Stewart said. “We would encourage citizens to go about their regular business during the holiday season but keep their eyes open.”

The state’s Joint Terrorism Task Force, made up of FBI and SLED agents, is “even more active” in light of the heightened alert, Stewart said, though he declined to discuss specifics.

Anyone who notices suspicious activity should contact their local police, Stewart said.

Midlands law enforcement agencies said they are aware of the heightened alert status, but none announced additional security plans .

Lexington County Sheriff James Metts said he reminded his patrol commanders to review emergency response plans for water, sewer and electrical plants in the county. Richland County sheriff’s spokesman Joseph Pellicci said his department is “doing a lot behind the scenes.”

Columbia police spokesman Skot Garrick said his department would be “paying close attention” to any suspicious activity at city utilities and City Hall.

Columbia-based utility SCANA Corp. has given extra protection to its Lake Murray dam, V.C. Summer Nuclear Station and other sensitive facilities.

“We can assure you that all our facilities are well-guarded and well-protected,” said SCANA spokesman Robin Montgomery. “We have been in a heightened state of security since 9/11. We take specific steps as a company as we reach (each) new alert level.”

For the State Ports Authority, the heightened security alert means balancing extra safety concerns against the need to move $90 million of cargo between boats, trucks and trains, said Byron Miller, spokesman for the authority. South Carolina has the fourth-largest container port in the nation for performing such work.

The ports authority is using individual vehicle inspections, video surveillance, night-vision equipment and thermal-imaging equipment.

Extra safety precautions come with an eventual price tag, Miller notes.

“Whenever you increase the alert level, that means more resources will be necessary to secure our ports,” Miller said.

Written by staff writer James D. McWilliams with reports from staff writers Rick Brundrett and Dave L’Heureux and The Associated Press. Reach McWilliams at (803) 771-8308 or jmcwilliams @thestate.com.