TRENTON, N.J. — With a hot sun bearing down, Gov. Chris Christie grasped a ceremonial shovel and dug into a patch of dirt where a new park would bloom in a blighted area of Newark.

To his right, holding another shovel, was Bill Baroni, then Christie's appointee at the Port Authority of New York and New Jersey — and now a central player in the George Washington Bridge scandal that has enveloped the New Jersey governor and his aides. Baroni was delivering a $9-million boost from his agency's coffers to buy land for the park.

The 12-acre stretch of grassy lawns, sports fields and playgrounds, which opened in 2012, has little to do with the Port Authority's primary mission: running the region's transportation network.

But it did put a smile on the face of one of Christie's key political allies, Essex County Executive Joseph DiVincenzo Jr., who stood next to the governor with a third shovel. One year after the park opened, DiVincenzo, a Democrat, snubbed his party's nominee for governor and endorsed Christie's reelection campaign.

"When you support somebody, you're supposed to be first in line. That's the way politics is," said DiVincenzo. He said the money was deserved because the Port Authority had stuck his county with a nearby incinerator and pollution from Newark Liberty International Airport. "You have to be able to give back."

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The Port Authority is best known these days for the spiraling controversy over allegations that Christie's allies at the agency worked with the governor's office to intentionally snarl traffic leading to the busiest bridge in the world in September, after a local mayor did not endorse Christie for reelection. On Friday, one of the governor's former Port Authority appointees, David Wildstein, said Christie knew more about the lane closures than he had acknowledged.

Problems at the Port Authority run deeper than the ongoing scandal, critics say. They say that Christie, a potential Republican presidential contender who rose to prominence as a corruption-fighting U.S. attorney and pledged as governor to reel in arcane government commissions, has used the agency to reward his friends and allies.

The troubled organization is the largest of its kind in the country, with a $7-billion budget, more than 7,000 employees, a dysfunctional management structure and a reputation as a secretive patronage haven.

Jointly controlled by the governors of New York and New Jersey, it owns the World Trade Center, airports, bridges, tunnels and the seaport, the nation's third-largest after the ports of Los Angeles and Long Beach. It operates a train and spearheads its own development projects. All of that money and hiring power has been an irresistible temptation to politicians on both sides of the Hudson River, which divides the two states.

More than a year before the current controversy, former Executive Director Stephen Berger described the Port Authority as "a money tree, an ATM machine," during a breakfast event in New York. "It's been a place [governors] can go to do projects they can't get through their budgets," he said.

Besides the park in Newark, agency money has recently found its way to roadway improvements in Union City, N.J., whose Democratic mayor, Brian Stack, also endorsed Christie. (Mark Albiez, a spokesman for the mayor, said the city "is proud of that money," which would help rehabilitate roads that lead to a Port Authority-operated tunnel.) The governor also secured cash to pay for New Jersey transportation projects such as renovating the Pulaski Skyway, a state-owned bridge, thus helping him avoid an increase in the state's gas tax, one of the lowest in the country.

Christie has stacked the Port Authority with dozens of loyalists, according to a list that surfaced in a recent lawsuit. One referral, who became a senior project manager, was a former Republican Party official who helped Christie run up big numbers in a key county during his first governor's race in 2009. And when Christie's nominees for judgeships have stalled, some have found a home in the authority's legal office.

Jameson Doig, a Dartmouth professor who wrote a book about the Port Authority called "Empire on the Hudson," said that other governors also had used the agency as a jobs bank — but that Christie had taken it to new heights.

"He viewed the Port Authority in a distinctly political way, the kind of way that the original design doesn't suggest," Doig said.

Christie spokesman Colin Reed did not respond to questions about Christie's Port Authority record. Instead, he released a statement that said Christie was confident that Deb Gramiccioni, whom he appointed to replace Baroni after the bridge controversy prompted Baroni's December departure, has a "proven record of rooting out corruption." The governor's office has denied Wildstein's latest allegations, which were included in a letter from his lawyer. Wildstein also resigned in December; he is seeking immunity from the U.S. attorney's office, which is examining the lane closures.

The Port Authority was created in 1921 with the hope that it would keep the area's vital transit mechanisms above petty and myopic local politics. It hasn't worked out that way.

In the 1990s, a battle for control between two Republican governors, Christine Todd Whitman of New Jersey and George Pataki of New York, led to a fateful compromise: New York would still choose the executive director, but New Jersey would pick a deputy. The result has been an agency often at war with itself.

"It's an unmanageable organization," said Martin Robins, a former Port Authority official and the founding director of the Alan M. Voorhees Transportation Center at Rutgers University.

In 2012, an internal study concluded that the agency was a "challenged and dysfunctional" mess, with poor leadership, little coordination on projects and a "lack of transparent and effective oversight" of the $14.8-billion effort to rebuild the World Trade Center. Other audits, by the state of New York, have found the Port Authority sagging under giant overtime bills and mushrooming spending.