When Boston annexed Hyde Park 100 years ago, Herman Bean bought a simple Victorian with a fenced-in yard on a bend of River Street.
The house was a pinnacle of achievement for the African-American factory worker. Five generations of Beans would grow up there, in what is still considered one of the city’s safest, more scenic, and, some would argue, suburblike neighborhoods.
But in recent years, Bean’s descendants and hundreds of other residents of a triangular section on the neighborhood’s border had to battle the US Postal Service in order to establish that they are, in fact, in Hyde Park, not in neighboring Mattapan where poverty rates and crime are higher.
The Postal Service had designated them as living in Mattapan with the 02126 ZIP code. But the designation irks residents who say it has led to great anguish and a host of ills, such as higher insurance rates and lower property values. It has also associated them with a neighborhood that some politely say has just never been their home.
“For me, it’s not an ‘us vs. them’ kind of thing because Mattapan has always been a thriving community,’’ said Barbara Hamilton, Bean’s great-granddaughter, as she sat, deed in hand, in the house where her 88-year-old mother still lives. “But when Pa Bean bought this house, he bought it in Hyde Park.’’
Earlier this month, after a petition from residents, the Postal Service retreated from its long-held stance on the matter, announcing that on July 1 it will change the ZIP code for 1,655 addresses to Hyde Park’s 02136.
The decision, hailed by residents and lawmakers, is only the second time the Postal Service has changed a ZIP code in Boston, Postal Service officials said. Four years ago, the agency relented to public pressure and restored the West Roxbury 02132 ZIP code to 680 West Roxbury addresses that had been switched to 02131, Roslindale.
“I learned a long time ago that you don’t tell people where they live,’’ said US Representative Michael Capuano, Democrat of Somerville, who helped residents push for the ZIP code change in Hyde Park. “Boston is not as clearly defined as people would like to think.’’
And there is truth to residents’ claims that it affects them financially. “It is a common and time-tested practice for insurance companies to include ZIP codes as one of the factors in determining premiums,’’ said Frank O’Brien, a vice president for the Property Casualty Insurers Association of America, a trade association with 1,000 members in Massachusetts.
According to the state Division of Insurance, premiums generally run higher in Mattapan than they do in Hyde Park. And drivers living in the Mattapan ZIP code could pay about $300 more annually for car insurance than their neighbors over the border, even just across the street, said Insurance Commissioner Joseph Murphy.
The insurance division noted in 2010 that residents of the disputed part of the Mattapan ZIP code actually live in Hyde Park and informed insurers that they should adjust their rates, Murphy said.
Rate changes at borders to poorer neighborhoods are a touchy subject, both among insurers and residents, because of past accusations of discrimination. Murphy said there is no indication of unfair or discriminatory practice along the Hyde Park-Mattapan border and that his investigators have not received any complaints from residents there in the past two years.
“There is nothing prohibiting a company from using ZIP codes for rating territories,’’ he said.
Although both neighborhoods are situated at the foot of the Blue Hills and have rich ethnic diversity, Hyde Park is a different place from Mattapan. Hyde Park has the prestige of being the mayor’s hometown. It boasts a clean business district with sit-down restaurants, a newly renovated YMCA, a golf course, and a tranquil natural reserve.
Mattapan is often perceived negatively. While it has seen pockets of revival - such as a newly rising community health center - it leads Hyde Park in nearly every category of crime, including homicides. In 2010, for example, 20 people were killed in Mattapan, compared with four in Hyde Park, according to police crime data.
According to the Warren Group, the median sale price for a single-family home in Mattapan last year was $200,000, compared with $279,000 in Hyde Park.
“I have had so many houses where the deed said Hyde Park but the post office said Mattapan, and the buyers would not even look at them,’’ said Pat Tierney, a longtime real estate broker who works in both neighborhoods. “People have in their mind that Hyde Park is a better place to live than Mattapan.’’
Boston Postmaster James J. Holland says the triangular patch at the Mattapan-Hyde Park line has been 02126 since ZIP codes were implemented in the 1960s. Residents may not have noticed it was a Mattapan ZIP code because their mail was sorted at a Hyde Park post office branch and then sent to Mattapan for delivery, Holland added.
But in April 2009, the cash-strapped Postal Service began sending the mail directly to the Mattapan Post Office.
Hamilton, who heads the East River Street Neighborhood Association, began working with members of other neighborhood groups after residents began complaining that the 02126 ZIP code was negatively affecting them. During a two-year campaign, they petitioned the Postal Service to change the ZIP code to Hyde Park.
They solicited help from their city councilor, state representative, and congressman and scoured record books, digging up age-old deeds and a map that showed the border of Hyde Park when it was annexed to the city in early 1912.
They also gathered signatures at voting places during the last election, collecting more than 800 from people who also felt slighted. The Postal Service finally relented.
“It came to a point when we said that we are going to have to challenge the US government,’’ said Hamilton. “There were so many facets of business that have adopted the ZIP code system.’’
Correction: An earlier version of this story had the incorrect ZIP codes for West Roxbury and Roslindale.