Fueled by a robust economy, and despite higher gasoline prices, a record 39.3 million Americans are expected to kick off the unofficial start of summer with Memorial Day Weekend trips, the AAA said.

This weekend’s travel volume could climb 2.7 percent over the same period last year, reaching the highest level since 2005, the auto club said. The AAA defines the travel weekend as Thursday through Monday and counts trips of 50 miles or more away from home, it said.

Saturday’s sunshine and mild temperature, with a high of 70 degrees, according to the Upton-based National Weather Service, might encourage travelers, though there is a 50 percent chance of rain Sunday.

Those who return Monday might be tempted to stay a little longer, as the forecast for rain falls to 30 percent, while the thermometer will reach 69.

While anti-traffic apps might help them avoid jams, air travelers could encounter airport construction delays at Kennedy, which is rebuilding one of four runways, and LaGuardia, where the redevelopment of Terminal B, which serves nine airlines, has snarled traffic on access roads.

The number of people behind the wheel should hit 34.6 million, the AAA said.

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“A good economy puts extra money in the pocket and people plan to spend it over the Memorial Day Weekend,” said Robert Sinclair, spokesman for AAA Northeast.

Locally, the average price of a gallon or regular gas on Long Island is about $2.52, up 11 cents from this time last year, according to the AAA website.

After Manchester’s deadly suicide bombing, officials said they were increasing security at possible targets, including mass transit, bridges, tunnels, airports — and the annual Bethpage Air Show at Jones Beach State Park.

Stepped-up security measures include more patrols, special weapons units and other equipment, and random bag and vehicle checks.

The air show, on Saturday and Sunday from noon to 5 p.m., is one of the holiday’s most predictable traffic jams.

Rising early is advisable; parking lots often fill by 11 a.m.

An alternative is attending Friday’s rehearsal, also from noon to 5 p.m., when all the performers, including the U.S. Air Force Thunderbirds, the U.S. Army Golden Knights, and a bevy of individual stunt pilots will perform.

For the fourth Memorial Day Weekend in a row, air travel will grow, the AAA said, rising to nearly 3 million passengers.

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The Port Authority of New York and New Jersey expects 1.8 million passengers at its airports, a 1.4 percent increase over last year. Kennedy should be the most popular, with 839,000 passengers, followed by Newark Liberty with 576,000, and 384,000 at LaGuardia Airport.

“Hundreds” of customer care representatives at the airports will aid travelers, the bi-state agency said.

About 3.4 million drivers will travel through Port Authority bridges and tunnels, the agency said, promising to suspend all but emergency construction and staff a “full complement” of toll collectors. Port Authority Police will conduct DWI checks.

Other travel methods this weekend — train, bus or boat, for example — will rise 2.9 percent, to 1.75 million, the highest since 2009, AAA said. Airports could be crowded all summer; more than 234 million people could fly between June 1 and Aug. 31, Airlines for America recently estimated.

That would be a 4 percent increase over the nearly 225 million who flew during the same period last year, the airline industry group said.

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Summer vacationers flying from Kennedy Airport Terminals 2 and 4 should clear security more swiftly due to new automation, according to TSA. Improvements include bins large enough to hold wheeled luggage, and automated rollers that carry them to be X-rayed, the agency added.

During the busiest summer days, clustered around Memorial Day, July Fourth and Labor Day, the TSA said it expects to screen more than 2.5 million passengers per day nationwide.

This summer, the TSA is stepping up U.S. airport security by deploying 50 more canine teams and 2,000 more TSA officers than last year.

“As we approach the summer break, securing the travel of millions of passengers daily remains our top priority,” said TSA acting administrator Huban A. Gowadia.