Amazon sent commercial real estate into a frenzy Thursday when the e-commerce giant announced the 20 finalists for its second North American headquarters.

Chicago made the cut in a list heavy on East Coast cities and the reasons why are as clear as the skies on this sunny day in the Windy City. The proposal put together by Mayor Rahm Emanuel and Gov. Bruce Rauner included 10 sites, many of them with large tracts of contiguous land for Amazon to develop.

Those include Sterling Bay's 70-acre Lincoln Yards, Related Midwest's 62-acre South Loop site, "the 78," which will already be home to a tech incubator run by the University of Illinois system, Farpoint Development's redevelopment of the Michael Reese Hospital Site, and even dark horse sites like the Illinois Medical District, McDonald's soon-to-be-vacant Oak Brook Campus and the Motorola Solutions campus in Schaumburg.

One of the strongest possible Amazon HQ2 sites is The River District, Riverside Investment & Development's planned redevelopment of the Chicago Tribune's printing plant in River West. NKF Executive Managing Director Geoff Kasselman told Bisnow in September this 37-acre site may offer the best location. Kasselman said The River District is the "doughnut hole," with the ability to connect downtown, River North and Fulton Market to the outlying neighborhoods.

Amazon is believed to be intrigued by the possibility of a second headquarters outside the Loop. Amazon officials were spotted last month touring the Lincoln Yards site. At Bisnow's Chicago creative office event last week, Merit Partners partner Paul Fishbein said all of the sites Amazon visited during its visit were outside of the central business district. R2 Cos. Managing Principal Matt Garrison said public transit limitations around the North Branch Industrial Corridor, which includes Lincoln Yards, are not a barrier. Sterling Bay has plans to extend the 606 to Lincoln Yards, and workers can use Uber or Lyft to commute to work for less hassle than taking public transit.

If Chicago wins the bidding, Emanuel and Rauner are believed to be offering at least $2B in incentives to Amazon, including returning $1.3B in tax revenue collected by Amazon employees back to the company.