The super-sized anti-gun violence billboard stretching along the Massachusetts Turnpike, long an unofficial Fenway Park landmark, will need to relocate by March 2015 due to a property sale.

John Rosenthal, founder and chairman of the Newton-based non-profit organization Stop Handgun Violence, attached the billboard in 1995 to the side of a parking garage he owned on Lansdowne Street. Since establishing the advertisement, Stop Handgun Violence has changed the billboard approximately once a year.

Currently, the billboard displays the number of gun deaths in the United States since the Sandy Hook Elementary School shootings in Newton, Connecticut in 2012, which took the lives of 20 first graders and six adults. The Boston Red Sox purchased the parking garage from Rosenthal last year under the agreement that he could continue to display the billboard until March 2015.

“It’s been a Boston landmark for a long time,” Rosenthal said. “I wish I didn’t have to relocate it because it’s become very iconic in this location, but I don’t own the building any longer, and I’m excited and hopeful about looking for a new, permanent home.”

Rosenthal said he is hoping to relocate the billboard to a busy road such as Interstate 93 or Route 128. Ideally, he said, it will remain in Boston.

Since purchasing the parking garage from Rosenthal, the Red Sox have not required Stop Handgun Violence to pay rent for the billboard. Rosenthal said high rent in a different location may keep the organization from finding a new home for the billboard.

“We’re hoping to find a location where we don’t have to pay rent, we’ll just have to pay to relocate the billboard,” he said. “So we need to find a property owner who shares our concern about gun violence.”

Rosenthal said the billboard’s message reflects the goals of Stop Handgun Violence, which include educating the community and encouraging citizens to become active participants in a reasonable dialogue about addressing gun violence.

“It’s changing the debate about gun violence from the polar extremes of unrestricted access to guns or banning guns to, ‘How can we reduce injuries and deaths from gun violence without banning guns?’” he said. “We’re constantly looking for solutions, and the billboard is a reminder that 83 Americans die every day from guns and that there isn’t even a background requirement in 33 states.”

Red Sox spokesperson Zineb Curran said Rosenthal has not asked the team for an extension of the March deadline, and the Red Sox intend to assist Rosenthal through the transition.

“Since purchasing the garage more than a year ago, John has not asked for an extension of his billboard easement rights, and we have had no discussions about our plans next year,” she said in an email Wednesday. “We will work with John in the coming months as he looks for a new home for his billboard, as was originally planned.”

Rosenthal said there was no need to ask the Red Sox for an extension because he no longer owns the building, and he agreed to the March 2015 deadline upon its sale.

Other members of the Boston community have expressed interest in ensuring the billboard remains a part of the city, including Boston Mayor Martin Walsh.

“Curbing the flow of illegal guns on the streets of Boston is one of the keys to stopping violence on our streets,” Walsh said in a statement Wednesday. “The Stop Handgun Violence Now billboard is an eye-opening reminder of the tragedy of the crimes being perpetrated with guns across our nation.”

Walsh, who is an active member of Mayors Against Illegal Guns and has facilitated numerous anti-violence efforts in the city of Boston, including a recently-instated gun buy-back program, said he would like to see the billboard’s continued presence in the city and is open to assisting in finding it a new home.

For now, Rosenthal said he has not yet found a new location for the billboard.