When delegates and visitors arrive for the Democratic National Convention this month, it will mark the 12th presidential convention in Philadelphia history.

In 1848, the Whig Party nominated Zachary Taylor for president at the former Chinese Museum at Ninth and Sansom Streets. In 1856, the American Party chose Millard Fillmore as its candidate at National Hall, 12th and Market. Ulysses S. Grant was the Republican Party choice in 1872 at the Academy of Music, at Broad and Locust.

Just some of the history you can uncover at an exhibit showcasing Philadelphia's presidential convention history, 1848-2016, unveiled Thursday by former Gov. Ed Rendell, chairman of the Philadelphia host committee for the convention, at Philadelphia International Airport's Terminal A-East.

"What city in America has had the most conventions? Philadelphia. We've had the most conventions, by far, of any city," said Rendell, who praised the exhibit as part of an effort to prepare the city for visitors to the convention, which will be held July 25 to 28.

"The delegate experience in Philadelphia starts when they get off the plane, walk through the jetway, and put their feet on Philadelphia soil here at the airport. We want it to be a rich and exciting experience," he said.

Photographs, campaign buttons, ribbons, posters, and memorabilia documenting the city's six Republican and three Democratic conventions - and Whig Party, American Party, and Progressive Party conventions - will be on display for a year.

Philadelphia is the only city to have hosted three presidential conventions in one year. In 1948, the Republicans, Democrats, and Progressive Party gathered in the sweltering heat at the old Convention Hall, at 34th Street and Civic Center Boulevard.

"That was the first year conventions were televised live from morning until night," said Leah Douglas, airport exhibitions director and chief curator.

And it was the last time a convention was held without air-conditioning, said Douglas, who did research at the Library of Congress, Historical Society of Pennsylvania, and Athenaeum of Philadelphia.

The Inquirer and Daily News provided photos of the 2000 Republican National Convention at the First Union Center and nominee George W. Bush.

Inasmuch as the Democrats' 47th convention will not happen for three more weeks, Douglas said she will "make alterations once everything is official." The display currently reads: Democratic nominees for president and vice president to be determined.

Philadelphia International is gearing up to greet the influx of travelers with volunteers in terminals and baggage-claim areas to answer questions and direct delegates to shuttle buses to take them to their hotels.

Actors portraying Benjamin Franklin, Betsy Ross, and Andrew Hamilton will be on hand. Free snacks of soft pretzels and water ice will be available in baggage-claim areas.

Taxi cabs can get a free car wash on Thursday, July 21, in the taxi lot near Terminal A-West, courtesy of the airport. "We want to make sure we put the best foot forward for these visitors," said Chellie Cameron, airport CEO.

How many of the 50,000 visitors to the city will travel by plane, train, bus, or car is not yet known. You will need an airplane ticket to see the free exhibit, which is beyond security screening checkpoints.

The convention's transportation staff said it was still polling delegations to find out their travel plans and would not know for a week or two.

American Airlines, Philadelphia's dominant carrier with 433 daily flights here, said its planes are 87 percent full. American does not plan to add more flights, or bring in larger aircraft. Southwest and Delta Air Lines also do not intend to add flights.

United Airlines said it will add two nonstop flights on Friday, July 22, to accommodate mostly journalists and staff who will travel directly from the Republican National Convention in Cleveland to Philadelphia.

"A lot of people who attend the convention will take charter flights, so it may not necessarily be scheduled service that gets them to Philly," Cameron said. "There will be a lot of corporate jets that fly in for the convention.

"We're basing that on what happened during the Republican National Convention in 2000," she said. "Typically, those folks don't make their travel arrangements, or file flight plans, until closer to the convention. So we may not have an accurate count for quite some time."

The Transportation Security Administration said it is working with the city and convention officials to have sufficient personnel at airport security checkpoints. The bulk of the passengers will be there Friday, July 29, the day after the convention ends and people go home, said TSA spokesman Michael McCarthy. "We are preparing to make sure we have good projections on passenger volumes."

Typically, at large events, the TSA provides uniformed federal air marshals who work with local and state law enforcement to patrol train stations and airports. "We do this all the time, when there are larger events such as the DNC," McCarthy said. The patrols will be visible throughout the convention week, he said.

lloyd@phillynews.com

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@LoydLinda