New York state voters approved a ballot proposal to authorize a previous expansion of an upstate Olympic sports complex and add thousands of acres to forest preserves in the Adirondacks, according to unofficial results from the state Board of Elections.

With more than 99% of election districts reported, the measure passed by a margin of about four points. The proposal centers on Lake Placid’s Mount Van Hoevenberg sports complex in Adirondack Park, nearly 300 miles north of New York City. It asked voters to accept the expansion of the state-owned complex onto 323 acres of land that was supposed to remain undeveloped.

By amending the state constitution, the measure allows for the construction of a stadium on the center’s existing biathlon track, but bars more expansive development like rental cabins, zip lines and tall buildings. In exchange, the state is pledging to add 2,500 acres of forest in other parts of the Adirondacks, though exactly where still must be determined.

Raul Aguirre, executive director of the nonprofit Adirondack Council, an environmental group, celebrated the proposal’s passing.

“This amendment strengthens accountability for how state agencies manage and protect one of New York’s greatest natural assets, the public lands of the Adirondack Park,” Aguirre said in an emailed statement. “It represents a clear vote of confidence in both the Park’s wild lands and the communities that depend on them, enabling Lake Placid and its neighbors to sustain a vibrant winter economy as international sporting events bring visitors and athletes from around the world.”

While the measure passed statewide, New York City voters rejected it by nine points, according to unofficial city and state election results. Manhattan is the only borough in the city where voters approved the measure, by about a point.

The Mount Van Hoevenberg complex is the site of the first bobsled track in North America and hosted the Winter Olympic Games in 1932 and 1980. It is also home to dozens of miles of cross-country skiing trails, luge and skeleton tracks and athlete housing. The complex has cut trees to make way for its expansion over the past 40 years.

New York established Adirondack Park in the late 19th century, and at about 6 million acres, it remains the largest publicly protected land in the continental United States. Half of the land is protected by the state constitution to remain wild forest preserve. The other half is privately owned and features farms, camps, homes and more than 100 towns where about 123,000 people live.