The Postal Service last week announced plans to change the zip code for 1,655 addresses after residents claimed they lived in Hyde Park, even though the zip code indicated they resided in Mattapan.

The move, changing the zip code for the homes to Hyde Park (02136) from Mattapan (02126), has an effective date of July 1.

“Customers who will have their ZIP Code realigned will have an official notification by mail in late May explaining the realignment and what steps that they can take to ensure a smooth transition,” James Holland, postmaster for Boston, said in a letter to Mayor Thomas Menino. “Local postal officials have already undertaken the necessary steps to accomplish this dramatic change by the effective date."

Holland said in the letter, dated March 12, that the residents and elected officials made a “compelling case.”

District 5 City Councillor Rob Consalvo, who represents Hyde Park and Mattapan, and the East River Neighborhood Association, led the push for the change, pointing to annexation maps of Hyde Park that proved the homes had been saddled with the wrong zip code.

“In my opinion we had an ironclad case,” Consalvo said.

Consalvo praised community activists, who had not been expecting a final decision on the matter for several more weeks, for pushing the issue and “holding our feet to the fire as elected officials.”

“The community deserves all the credit,” he said.

The effort has been underway since 2009. In a 2010 letter to Holland, the neighborhood association argued that the Mattapan zip code led to a $100,000 difference in home value, increased car insurance costs, and refinancing and appraisal disparities.

The association believes the zip code switch originally occurred sometime in the 1980s.