A winter storm that barreled across the United States from Cedar Grove, Calif., where it dropped 49 inches of snow, to Ogunquit, Maine, which saw more than a foot, was finally departing on Tuesday, but not before giving New England one last whack.

Having come ashore from the Pacific a week ago as a “bomb cyclone,” the storm dropped at least four inches of snow in 30 states. Its mix of cold, wind, snow, sleet and rain shuttered schools, blocked hundreds of miles of highways, scuttered scores of flights and was linked to multiple deaths over the long holiday weekend in Missouri, Arizona and South Dakota.

Bob Oravec, a meteorologist with the National Weather Service, described the storm as “very long-lasting” and said it was rare for a storm to have that kind of staying power.

So how did the storm maintain its strength over such a long time and distance? As with other storms, the ebbs and flows of heavy to light snowfall associated with this one were predominantly dictated by topography, Mr. Oravec said.