Amazon's air cargo company made an initial approach to Denton leaders last fall about locating at the city's municipal airport.

The city's economic development department was compelled Monday to reveal Amazon Air's identity after a citizen won an open records request to force the disclosure. The city had given the inquiry a code name, "Project High Flyer," which the Texas attorney general's office ultimately ruled was not protected information and could be released.

No one at the city has heard from Amazon Air since the initial inquiry, said economic development director Caroline Booth.

Kelly Cheeseman, spokeswoman for Amazon, said the company is always evaluating its operations but declined to comment further.

The company's inquiry into Denton Enterprise Airport came about the same time Amazon announced in September that it was looking for a place to build its second corporate headquarters, known as HQ2. It isn't clear, however, if the interest Amazon Air has shown in Denton is part of the region's bid to lure the second headquarters.

Denton participated in the cooperative proposal the region sent to Amazon. Dallas is among the 20 finalists for the prized project that promises to bring 50,000 jobs to the winning city. Amazon's real estate team visited Dallas in mid-February.

Darren Grubb, spokesman for the Dallas Regional Chamber of Commerce, said he couldn't comment on the status of the region's HQ2 bid.

"It's reasonable to expect a growing company like Amazon to be working on multiple projects at the same time," Grubb said. "It may or may not be an indication of any decision related to HQ2."

Amazon Air has about 40 cargo planes, about half of which are based at its freight delivery service hub at Cincinnati/Northern Kentucky Regional Airport. Amazon Air has operations at 15 other airports around the country, including three in Texas: DFW International Airport, George Bush Intercontinental Airport in Houston and Lackland Air Force Base in San Antonio.

According to Ohio media reports, Amazon Air could grow to about 100 airplanes based in Ohio alone, with 15,000 employees. Amazon Air is also experimenting with delivery by drone, with development centers in the U.S. and abroad where engineers are building and testing the unmanned aircraft.

Denton has a peppered history with the use of code names for business projects. Through a contract with the city, the Chamber of Commerce fields many business prospects for Denton. Economic development officials at the chamber assign code names, whether or not the business has asked for a nondisclosure agreement.

Most negotiations handled in the city's economic development department aren't code-named, but a few have been, Booth said.

For example, WinCo Foods' distribution warehouse was code-named "Project Ranger One." When the business name was unveiled, taxpayers learned that the city landed one of its largest-ever economic investments, one that would jump-start other development in the new industrial park.

But when the city unveiled the business behind the code name "Project Cartoon," taxpayers learned the city had agreed to incentives for Buc-ee's. The deal to subsidize the travel plaza in exchange for financial help to accelerate improvements along Interstate 35E in southern Denton remains controversial today.

City Council has yet to authorize the city staff to enter into nondisclosure agreements for economic negotiations since hiring Todd Hileman as city manager in November 2016.

Denton veterinarian and open government activist David Zoltner made the initial records request after he saw Project High Flyer on a council closed session agenda. He pursued the information for months, even after he believed the project was likely dead.

"This was about the precedent, about who it is and not letting them [the city government] believe that every business prospect is confidential," Zoltner said. "That shouldn't be the way the game is played. Incentives, yes; but incentives and identity are different things."

Some businesses require a city to enter into a nondisclosure agreement to receive even preliminary information about a project, including the name of the company and the industry, Booth said. The company and the community often share sensitive information that allows for a cost-benefit analysis of the project, Booth said.

While discussions with Amazon Air went dormant after the initial inquiry, Booth said the city remains optimistic the company is still interested in the Denton airport. She said another company is visiting Denton this week after making its initial inquiry two years ago.

"After being in this role for a couple of years, until I've had a project locate somewhere else, I don't consider it done," Booth said.