NEWBURGH, N.Y. — After stocking up on sparklers and flaming fountains, Don Eason couldn’t resist adding one more impulse buy to his incendiary items: a Fiery Frog, which promises to erupt in a column of crackling, multicolor sparks.

“Daddy’s getting you a green thing, too,” he told his 3-year-old twin sons.

“Green!” Devine said enthusiastically, as his brother, Daylan, waved a box of sparklers and shouted, “Fireworks!”

For the first time in more than a century, shoppers like Mr. Eason can legally buy some small, consumer-grade fireworks in parts of New York State. They remain banned in New York City, but in November, Gov. Andrew M. Cuomo signed legislation allowing limited sales in counties that choose to permit them. More than 30 of New York’s 62 counties opted in, allowing “sparkling devices,” as the law refers to them, to be sold and used within their borders.

New York’s law is the latest outcome of a nationwide movement toward relaxing fireworks restrictions. Only three states — Delaware, Massachusetts and New Jersey — still ban all consumer sales, and this year, Georgia expanded its law, allowing a broader range of products to be sold.