(CNN) -- New York's One World Trade Center will be the United States' tallest building after all, according to the group that decides such things.
The New York building will indeed officially be 1,776 feet tall as previously publicized, meaning it will take the U.S. title from Chicago's Willis Tower -- at 1,451 feet -- when it is completed next year, the Chicago-based Council on Tall Buildings and Urban Habitat said Tuesday.
At issue was whether the organization believed One World Trade Center's topmost structure will be a permanent spire, which counts toward height, or an antenna, which wouldn't have counted.
In a meeting the group held last week, the spire definition won out.
"The key word is permanence. The decision that antennae do not count in the height of a building is because antennae are not permanent to the building design," CTBUH Executive Director Antony Wood told reporters in Chicago. "... The committee were quite clear that that was not the case on One World Trade Center. ... We know that it's a permanent feature because of the sacrosanct aspect of the 1,776 height.
"In other words, that crowning structure is never to be added to, never to be taken away."