PLYMOUTH, N.H. — It slammed into land and rapidly moved north, destroying buildings, altering coastlines, ripping apart forests and shocking a population that had never experienced a hurricane.

About 700 people died 75 years ago when the storm known variously as the Great New England Hurricane of 1938 or the Long Island Express began plowing up the Northeast coastline at 2:45 p.m. on Sept. 21, 1938.

A weather station in Massachusetts recorded sustained winds of 121 mph and gusts as high as 186 mph — a major storm by modern standards that dwarfs the land wind speeds recorded in storms Irene and Sandy, which also devastated parts of the Northeast in recent years.

“It was the strongest, the most devastating, the deadliest and the costliest for the region and still is,” says Lourdes Aviles, a Plymouth State University meteorology professor in Plymouth, N.H., who this month published the book “Taken by Storm, 1938: A Social and Meteorological History of the Great New England Hurricane.”

The hurricane was the death knell for many mills and factories that had barely survived the Great Depression. It stripped 4 million bushels of apples from orchards, killed livestock and felled millions of trees, according to Aviles’ research. Bridges and dams were destroyed, and rail travel was halted for weeks.

The hurricane’s death toll varies from 500 to 800, depending on the source. Aviles adopts the Works Progress Administration’s count of 682. Tidal surges as high as 26 feet were recorded, and Rhode Island suffered the most casualties.

The storm was notable not only for the death and destruction it spawned, but also the forward speed that gave it one of its nicknames. It hit Long Island, N.Y., and southern Connecticut moving at an amazing 47 mph, according to the National Weather Service.

Despite the recent woes brought by Sandy and Irene, any similar storm in the future will beset a population that has no appreciation of what a true hurricane is, Aviles says.

“No matter what storm you think about in the last century,” she says, “nothing here compares with 1938.”