Be prepared for a bumpy start if you're planning a vacation this summer and flying out of New York or another busy airport.

An estimated 231 million passengers — an all-time high —  are expected to fly in the United States between June 1 and Aug. 31, according Airlines for America (A4A) — the industry trade organization whose members include American Airlines, United, Southwest and JetBlue.

The group foresees a total of 2.5 million passengers per day, a prediction that would further snarl airports already dealing with massive lines at security checkpoints, manned, critics say, by too few federal screeners having to inspect too many carry-on bags.

The waits at New York-area aiports have gotten so out of hand that New York's Sen. Charles Schumer has called on the Transporation Security Administration to increase the number of screeners and canine teams to speed up the lines.

“As New York City airport wait times bog down, so waits the nation,” Schumer said. “New York City is a national hub and if we can reduce the wait times here, we can make the entire country move a lot faster.”

Neither Boston's nor Philadelphia's airports have seen lines like those in New York airports or Chicago's O'Hare International Airport, where thousands have missed flights while waiting in security lines. On Tuesday, the TSA promised to bring in hundreds of additional employees to O'Hare and TSA Administrator Peter Neffenger apologized to passengers left stranded after missing flights.

At Boston's Logan Airport, wait times have been 20 minutes or less, according to Jennifer Mehigan, spokeswoman for Massport, which oversees the airport. TSA staffing has been adequate at Logan, she said, although passengers are still encouraged to arrive two hours prior to departure for domestic flights and three hours for international flights to “avoid unforeseen delays.”

Passenger traffic at Philadelphia International Airport is just now approaching pre-2008 recession levels, according to spokeswoman Mary Flannery.

“At Philadelphia International Airport, our lines and our wait times are not nearly as extreme as in some other airports,” Flannery said. “We have several ways in which we've been working with the airlines and the TSA to try to mitigate wait times.”

Nevertheless, Pennsylvania's Democrat Sen. Bob Casey issued a statement Wednesday calling for more funding for the TSA so that it can boost staffing at airport security checkpoints.

“With summer travel season quickly coming upon us, it is vital that steps be taken to reduce the long lines at our airports,” he said. “We must do everything we can to keep air travel safe, reliable and efficient. Appropriately funding TSA will do just that.”

According to Casey, TSA has lost $250 million in funding since 2011, while the number of passengers screened in 2015 was 708 million, an increase of 40.7 million over 2014.

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The Port Authority of New York and New Jersey said Wednesday that security lines are a TSA matter, but added the agency sent a letter to the TSA pointing out the need for sufficient staffing to reduce wait times.

In the letter, the Port Authority stated that the maximum average wait time at JFK International Airport between March 15 and April 15 increased 82 percent from the same period in 2015. Maximum wait times at JFK were about 55 minutes — with similar situations at LaGuardia and Newark airports.

The reasoon for the long waits at airports, according to CNN, is threefold: more travelers; budget cuts that have stripped TSA of thousands of screeners; and passengers loading up their carry-ons to avoid airlines' fees for checked baggage.

The TSA has 42,525 frontline staffers this year — a 10 percent decrease since 2013, CNN reported. The agency is expected to try to have 768 new security officers by mid-June and current officers are being offered overtime.

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“TSA’s primary focus is the current threat environment, as the American transportation system remains a high value target for terrorists,” the TSA said in a statement. “Our strong economy means air carriers are enjoying record travel volume, which is resulting in heavier than normal volumes of travelers at our nation’s airports — some with double digit increases over last summer.”

To help ease the chaos at airports, the TSA recommends that passengers arrive early to the airports; prepare bags for security; be ready when entering a checkpoint line; and reach out to the agency if there are any questions.

The agency also urges travelers to enroll in PreCheck, which costs $85 for five years, enabling travelers to pass through an expedited screening.

“Traveler security is TSA’s first priority and we remain intensely focused on our important mission,” the statement said.