Question: As of 2018 , what was the estimated population of the United States city with the Willis Tower ?

text: List of tallest buildings in the United States
Tallest buildings by pinnacle height
This lists ranks completed and topped out buildings in the United States that stand at least 800 feet ( 244 m ) tall based on pinnacle height measurement , which includes antenna masts . Standard architectural height measurement , which excludes antennas in building height , is included for comparative purposes . Tallest buildings in the United States , by pinnacle height , including all antennae , poles , etc . whether architectural or not ( 2020 ) .
The world's first skyscraper was built in Chicago in 1885. Since then, the United States has been home to some of the world's tallest skyscrapers. Eleven American buildings have held the title of tallest building in the world (9 in New York City). New York City and Chicago have always been the centers of American skyscraper building. The 10-story Home Insurance Building, built in Chicago in 1885, is regarded as the world's first skyscraper; the building was constructed using a novel steel-loadbearing frame which became a standard of the industry worldwide. Since its topping out in 2013, One World Trade Center in New York City has been the tallest skyscraper in the United States. Its spire brings the structure to a symbolic architectural height of 1,776 feet (541 m), connoting the year the U.S. Declaration of Independence was signed, though the absolute tip (or pinnacle) of the structure is measured at 1,792 ft (546 m). However, the observation deck elevation and highest occupied floor of One World Trade Center are surpassed by 432 Park Avenue and Chicago's Willis Tower (formerly and still commonly known as the Sears Tower). Steinway Tower, and Central Park Tower will also have higher occupied floors and roofs upon their completion. Prior to the September 11, 2001 attacks in New York City, the twin towers of the World Trade Center occupied the second and third positions on the list below, behind Willis Tower. The North Tower stood at 1,368 feet (417 m), while the South Tower was 1,362 feet (415 m) tall.
Rank Name City Pinnacle height ft ( m ) Architectural height ft ( m )
1 One World Trade Center New York City 1,792 ft ( 546 m ) 1,776 ft ( 541 m )
2 Willis Tower Chicago 1,729 ft ( 527 m ) 1,451 ft ( 442 m )
3 Central Park Tower New York City 1,550 ft ( 472 m ) 1,550 ft ( 472 m )
4 John Hancock Center Chicago 1,500 ft ( 457 m ) 1,127 ft ( 344 m )
5 Empire State Building New York City 1,454 ft ( 443 m ) 1,250 ft ( 381 m )
6 111 West 57th Street New York City 1,428 ft ( 435 m ) 1,428 ft ( 435 m )
7 One Vanderbilt New York City 1,401 ft ( 427 m ) 1,401 ft ( 427 m )
8 432 Park Avenue New York City 1,396 ft ( 426 m ) 1,396 ft ( 426 m )
9 Trump International Hotel and Tower Chicago 1,389 ft ( 423 m ) 1,389 ft ( 423 m )
10 30 Hudson Yards New York City 1,268 ft ( 386 m ) 1,268 ft ( 386 m )
11 Bank of America Tower New York City 1,200 ft ( 366 m ) 1,200 ft ( 366 m )
12 Aon Center Chicago 1,136 ft ( 346 m ) 1,136 ft ( 346 m )
13 Comcast Technology Center Philadelphia 1,121 ft ( 342 m ) 1,121 ft ( 342 m )
14 Condé Nast Building New York City 1,118 ft ( 341 m ) 809 ft ( 247 m )
15 Wilshire Grand Center Los Angeles 1,100 ft ( 335 m ) 928 ft ( 283 m )
16 3 World Trade Center New York City 1,079 ft ( 329 m ) 1,079 ft ( 329 m )
17 Salesforce Tower San Francisco 1,070 ft ( 326 m ) 1,070 ft ( 326 m )
18= Chrysler Building New York City 1,046 ft ( 319 m ) 1,046 ft ( 319 m )
18= The New York Times Building New York City 1,046 ft ( 319 m ) 1,046 ft ( 319 m )
20 Bank of America Plaza Atlanta 1,040 ft ( 317 m ) 1,023 ft ( 312 m )