MINEOLA, N.Y. — Electric utilities that spent billions of dollars hardening infrastructure after Superstorm Sandy hit New York and New Jersey in 2012 say those upgrades helped keep the lights on during last weekend’s blizzard.

The wind whipped and the snow piled up by the foot, but compared to many previous storms, power outages were mild.

Consolidated Edison, which serves 3 million customers in New York City and its northern suburbs, reported only 4,500 customers lost power. On Long Island, where Atlantic storms have a history of playing havoc with overhead power lines, utility PSEG reported that fewer than 30,000 of its 1.1 million customers had an outage.

Jersey Power and Light saw 130,000 of its 1.1 million customers lose service, but spokesman Ron Morano said more than three quarters of those people had service restored within 24 hours. Another New Jersey utility, Public Service Electric & Gas, had only 5,700 total outages.

Utilities and some experts said things could have been a lot worse if the companies that oversee the power grid hadn’t learned such hard lessons during Sandy, when 4 million customers in the two states lost service.

“Certainly all the improvements utilities made post-Sandy; the hardening of infrastructure, the tree-trimming, replacement of wires and switches all were really necessary and contributed to keep the outages down,” said Meghan McPherson, an emergency management expert.

Besides installing wider, heavier power poles and more resilient wiring, Con Edison spokesman Phillip O’Brien said the company has installed “smart switches” in many areas. The switches are designed to limit the number of customers who lose service when an individual wire or a pole goes down.