Mayor Thomas Menino was sworn in for a fourth term on Monday, telling Bostonians the city's future is bright, despite the recent loss of homegrown corporate giants and a wave of violence that pushed the number of homicides to a 10-year high.

The Democratic mayor, in line to become the city's longest-serving mayor, urged residents to celebrate the "strength of Boston's neighborhoods," which are blessed with a spirit of "tolerance and togetherness."

"We must protect it against windy naysayers, those who read doom and gloom into every event of every day's news," Menino said in his speech at Faneuil Hall.

The 75 homicides in Boston last year — the most since 1995 — made national headlines. Menino urged residents who know someone with an illegal gun or who have witnessed to a crime to "speak up and keep the specter of fear from our neighborhoods."

He said does not believe that the acquisitions of Boston institutions like FleetBoston and Gillette Corp. by out-of-state companies were signs that the city was losing its economic clout.

"This is a misguided interpretation," he said. "Boston's economic lifeblood is the currency of our ideas, our innovation, and our creativity."

Fleet was bought by North Carolina-based Bank of America in 2004, while Gillette was acquired last year by Cincinnati-based Proctor & Gamble.

Menino also announced that the Massachusetts Port Authority has struck a deal with Hainan Airlines to provide nonstop service between Logan International Airport and Beijing — the China-based airline's first direct service to the U.S.

Mayor Kevin White also served four terms, from 1968 to 1983, but Menino served an additional four months as acting mayor after his predecessor, Raymond L. Flynn, left office in 1993 to become ambassador to the Vatican.