The Staten Island Advance chronicled Molinari family events, from the birth of a grandchild to a cat’s new litter. Everyone called him Guy, and voters were not surprised when he knocked on their doors or slapped their backs at the supermarket.

In an overwhelmingly Democratic city, Mr. Molinari was one of the prominent Republicans of his era, a forceful advocate for 380,000 islanders, many of Italian and Irish descent and many of them police officers, firefighters and civil servants, who often seemed to regard the problems of the rest of New York City across the harbor as distant thunder.

In Albany and Washington, he fought for better transportation and against pollution in his borough, the site of many oil depots. He successfully opposed a new power plant, and he won a bid to cut tolls on the Verrazano-Narrows Bridge for residents. He also took an obligatory stance for Staten Island’s secession from the city, a hopeless yet perennial issue among islanders who felt they received short shrift.

As borough president, Mr. Molinari played a key role in closing the Fresh Kills landfill on the island’s desolate western shore in 2001, ending its more than half-century distinction as the prime dumping ground for New York City’s garbage.

And at the helm of a formidable political machine, Mr. Molinari, one of the last of the city’s old-time power brokers, decided who would get patronage jobs and who among his protégés would run for the City Council and the Legislature, for judgeships and seats in Congress. Candidates who faced tough races were always assured of his presence on the campaign trail, which often guaranteed victory.

Although Staten Island has traditionally been a Republican bastion in the city, registered Democrats outnumber Republicans in the borough 3 to 2. But voters often cross party lines in general elections, splitting tickets and electing as many Republicans as Democrats. Mr. Molinari sometimes represented the Conservative and Right to Life Party lines as well as the Republican line on ballots.