New Haven’s infamous ice cream riot began on an afternoon in May 1952, when a Good Humor truck and an ice cream pushcart squabbled over a parking space in front of Yale Station. Yale students immediately defended the pushcart, leading to a scuffle with New Haven high school students who had been just dismissed from school. The students blocked Elm Street traffic, forcing the fire department to disperse the crowd by spewing water from fire hoses.

Over the past century, New Haven and Yale, now the city’s largest employer and historically one of its most visible entities, have endured town-gown riots, property disputes and lengthy court cases. At times, it looked like the more promising current relationship cultivated by Yale President Richard Levin and Mayor John DeStefano Jr. would never arrive.

Town-gown animosity during the mid-1900s often culminated in physical violence.

“Through the 18th and 19th centuries, and into the early 20th century, there were sporadic outbreaks of violence between local youth and Yale students,” said Gaddis Smith ’54, professor emeritus of history and expert on Yale’s past. “Every decade or so, there was a bad situation. Some were lethal.”

One of the last of the town-gown riots came on St. Patrick’s Day, 1959, when Yalies threw snowballs at a New Haven procession marching down a snow-filled Elm Street. The fracas that followed led to a few minor injuries.

Things took a turn for the better when City Hall and the University agreed on a large highway design to revamp New Haven’s transportation system. The same Elm Street hotspot featured in the 1959 riots would enter an underground tunnel at the Broadway Street parking lot and reemerge by the courthouse.

The University felt this would make it safer for students crossing the street, particularly since there was no traffic light at the Elm Street-High Street corner at the time. Incidentally, because of the high cost and unified neighborhood opposition, the highways never appeared. But the momentum paved the way for a number of other street changes. For two million dollars, Yale purchased two-block sections on both High Street and Wall Street, closing them to city traffic.

This was one of a number of similar property swaps that occurred throughout the 20th century. One of the most memorable happened in the 1920s, when Yale bought Library Street, now the walkway between Jonathan Edwards and Branford. In exchange, Yale sold to New Haven the land for Tower Parkway, now the street near Payne Whitney Gymnasium.

“This is part of a larger moving back of land and assets between the city and the University,” Smith said.

But as New Haven’s economic conditions worsened in the 1970s, a time which Smith said was a low point in Yale-New Haven relations, the city attempted to restrict Yale’s growth.

Local politicians began to focus more than ever on Yale’s tax-exempt status as a non-profit organization. Mayor Bart Guida established the Guida Amendment, stating that Yale could not acquire any new property without the city’s permission. The courts overturned the amendment after five years, but in the interim active plans to build additional residential colleges had to be abandoned and have never been revived, Smith said.

The state of Connecticut provided a solution to the tax exemption debate in 1978 with the Payment In Lieu Of Taxes program. Under PILOT, the state pays cities a certain percentage of the taxes cities would have received if non-profit properties were taxed. This allowed New Haven to better profit from Yale’s presence and even led city officials to encourage Yale’s expansion.

“Yale can hardly claim credit for the PILOT program, but it is the most important piece of legislation for the relationship between New Haven and Yale,” School of Management professor Douglas Rae said.

Currently, New Haven receives 77 percent of what it would receive if Yale had to pay property taxes, Smith said.

“The philosophy was that the benefit of Yale is to the state as a whole, and therefore the cost of that should be distributed to the state as a whole,” Smith said.

In 1993, John DeStefano Jr. became mayor of New Haven and Richard Levin president of Yale. This marked the start of a new era in town-gown affairs; in the past eight years, DeStefano and Levin have teamed up to found Yale’s Office of New Haven and State Affairs and inaugurate a number of new Yale-New Haven initiatives.

“We are now at an all-time high in Yale’s cooperation with city government,” Rae said. “That high began in the early ’90s.”

The city and University are devoting resources to bring new biotech firms to previously languishing Science Park. Meanwhile, the Broadway redevelopment plan has attracted shoppers back to downtown New Haven.

Yale, which pays taxes on all of its non-educational property, is now New Haven’s third largest taxpayer, said Hugh Eastwood ’00, a financial analyst for University Properties.

“President Levin has devoted more energy and more resources to New Haven than any previous Yale president,” Rae said.