Philadelphia has resumed its active courtship of Amazon's planned second headquarters after being named to the technology and retail giant's list of 20 locations under consideration for the new corporate campus.

City leaders were scheduled to speak with Inc. officials during a Friday conference call on the city's next steps in its proposal to host the office complex referred to by the Seattle-based company as its HQ2.

Other sites identified by Amazon as candidates for the new headquarters in a Thursday announcement included Pittsburgh and Newark in neighboring New Jersey, as well as urban powerhouses New York, Los Angeles, and Chicago, and technology centers such as Austin, Texas, and Boston.

The locations were among 238 to bid for the headquarters in response to a request for proposals issued only six weeks before the company's Oct. 19 deadline for submissions.

"Philadelphia's inclusion in Amazon's top 20 potential locations for HQ2 is an exciting milestone for the city," Mayor Kenney said in a release. "We are thrilled at today's announcement and look forward to working with Amazon's team on the next steps of this process to further highlight all that Philadelphia has to offer."

Amazon said in a release that it would now "work with each of the candidate locations to dive deeper into their proposals, request additional information, and evaluate the feasibility of a future partnership." The company said it hopes to pick a location before the end of this year.

At an afternoon news conference, Commerce Director Harold T. Epps said he felt "absolutely ecstatic" about the announcement, which has emboldened his team to aggressively court other companies seeking to expand. Potential targets include Apple Inc., which said Wednesday that it planned to open a new campus of its own in a yet-to-be named location, Epps said.

In the meantime, he said, his team has "got a lot of work to do" on the Amazon bid.

Amazon's plans call for spending more than $5 billion on the new corporate campus, where up to 50,000 people will be employed. The company has said it could eventually put 8 million square feet of offices at the site, an amount of space equal to almost 6½ Comcast Center towers.

In its request for proposals, Amazon had a wishlist for contenders, including populations of more than one million, an international airport, good transit systems, a wealth of colleges and universities, and more. It also said financial incentives would be "significant factors in the decision-making process."

The Philadelphia Industrial Development Corp., the city's nonprofit economic development agency, spent $160,000 in municipal stimulus funds and money from the Knight Foundation and the Chamber of Commerce for Greater Philadelphia on the city's bid.

Its pitch to the company consisted of an online suite of videos, interactive maps, and letters of endorsement to promote the city. A heavily redacted version of its formal 108-page proposal document, released last month in response to a request under the state's Right to Know act, offered no details about tax breaks or other financial incentives.

Chamber of Commerce president Rob Wonderling said in October before bids were entered that Pennsylvania officials were prepared to offer the company more than $1 billion in tax incentives if the state was selected. (Former New Jersey Gov. Chris Christie signed legislation earlier this month offering $7 billion in state and city tax credits for the company to locate in Newark.)

Philadelphia's pitch revolved around the Schuylkill Yards and uCity Square developments in West Philadelphia's University City, a dense enclave of educational and research institutions near the city's main train station, and South Philadelphia's Navy Yard, which offers plenty of open space for growth.

Epps said Thursday that he hopes to soon have an opportunity to guide company representatives on tours of both areas.

"If they want community, they'll go to West Philadelphia," he said. "If they want campus, they'll go to the Navy Yard."

William Hankowsky, chief executive of the Navy Yard's main developer, Liberty Property Trust, said Philadelphia's placement on Amazon's short list shows the city's attractiveness for companies and called on leaders throughout the region to support the bid as a whole.

"Like the Eagles, we had a great season," he said, in reference to the Philadelphia team's advancement to this weekend's conference championship game. "Now that we're in the playoffs, we need to play as one team, execute perfectly, and bring it home."

Already on Thursday, nearby municipalities that had submitted bids of their own were coalescing around Philadelphia's efforts.

Camden County officials, whose proposal did not make the list of 20 finalists, expressed enthusiasm over Philadelphia's place among the chosen cities, saying that South Jersey will benefit if its neighbor is selected.

Leaders in Delaware, which had proposed three sites in the state to Amazon, expressed a similar sentiment.

Gov. Wolf, meanwhile, said it was "no surprise" to find Pennsylvania's two biggest cities on the company's short list.

Susan Wachter, a real estate professor at the University of Pennsylvania's Wharton School, said all the places making Amazon's shortlist, which also include Washington, Nashville, Dallas, and Raleigh, N.C., share an ability to attract talented workers to fuel the company's growth.

Amazon's final selection will take into account considerations such as cost of real estate, access to existing talent pools, and urban vibrancy, she said.

New York, for example, is a vibrant city with plenty of skilled workers, but it's an expensive market, she said. Montgomery County, Md., offers access to Washington's labor pool at a fraction of the price but lacks urban buzz.

Philadelphia, she said, stands out for having most of what Amazon wants if it's willing to compromise a little: a less vibrant urban center than New York or Chicago, but at a lower price; not right next to the big talent pools of New York or Washington, but not too far away either.

"There are obviously trade-offs Amazon is going to have to think through on this list," she said.

Holly Sullivan, an Amazon public policy official, said in the company's release Thursday that zeroing in on its 20-location shortlist had been a challenge.

"All the proposals showed tremendous enthusiasm and creativity," she said. "Through this process we learned about many new communities across North America that we will consider as locations for future infrastructure investment and job creation."