Amazon officials made a return visit to Chicago last month to check out a possible home for its next North American headquarters in the South Loop site — adding fresh speculation about the online retail giant’s tight-lipped search for the 50,000-job prize that comes with it.

Employees of the Seattle-based company in mid-August embarked on a second tour of a 62-acre riverside property known as “The 78,” sources familiar with the visit said Wednesday. The area, named in hopes the sprawling site becomes Chicago’s 78th neighborhood, is bounded by the Chicago River, Roosevelt Road, 16th and Clark streets.

Chicago is among 20 finalists that made the cut in January to be the home of HQ2, which Amazon said could bring 50,000 jobs to the region. The city has partnered with the state to offer a $2.25 billion incentive package to lure the facility here. Amazon’s decision is expected to be announced by the end of the year.

But plans from other developers suggest that The 78 is also slated to welcome a $1.2 billion public research and innovation hub, restaurants, bike paths, new residential and commercial buildings and at least one hotel. Should Amazon, which needs 8 million square feet for HQ2, turn to Chicago, future prospects for those projects would be unclear.

The company has remained mum about whether it has visited other Chicago sites or other cities. In March, Amazon employees surveyed The 78 and four other Chicago sites.

The other sites in the city included a Chicago River district where Tribune Media wants to build 15 office and residential towers; the Lincoln Yards site, former home of the Finkl Steel plant among 100 acres along the River; Fulton Market; and the Burnham Lakefront, an area that includes the old Michael Reese Hospital site.

The scramble by mayors across the nation to woo Amazon officially kicked off last September and has spanned 238 cities. Chicago is the largest Midwestern city still in the running. Columbus, Ohio, and Indianapolis are the closest other contenders that remain on Amazon’s list.

An Amazon spokesman declined to comment. Spokeswomen for Mayor Rahm Emanuel and Gov. Bruce Rauner declined to comment.