"There's a question that's looming over the new skyscraper at the World Trade Center site in New York: Should it count as the tallest building in the country?" ask David Schaper and Joel Rose. "The developers say yes. But by some measures, the Willis Tower in Chicago — formerly known as Sears Tower — can still lay claim to the title."
"Now, an obscure organization known as the Council on Tall Buildings and Urban Habitat [CTBUH] is preparing to settle the debate."
"What it really comes down to is this: What are we measuring?" asks Antony Wood, CTBUH's executive director. "If we are measuring man's ability to put materials above the plane of the earth, then it should just be material, irrespective of what that material or function is. Or, are we measuring man's ability to put man above the plane of the earth? Are we going with the highest occupied floor? Or something in between?"
UPDATE (11/12/13): The CTBUH has rendered its judgement and 1 WTC has been named the United States' tallest building. According to Kriston Capps, "The Council, which is housed out of the Illinois Institute of Technology (right there in Chicago!), determined that the spire on 1 WTC was a structural component of the building. The antennae at the top of Willis Tower, on the other hand, were deemed communication components, mere afterthoughts from a structural point of view."