WASHINGTON — Doors to the Barack Obama Presidential Center could open as soon as 2020, Obama Foundation chair Marty Nesbitt said Tuesday, though a decision on whether the library and museum will be in Jackson Park or Washington Park is months away.

On Tuesday, President Barack Obama and first lady Michelle made it official and picked Chicago’s South Side to be the future home of their library, museum and foundation, not a surprise since word leaked out weeks ago.

The center will be associated with — but independent of — the University of Chicago, one of four universities bidding for the project.

U. of Chicago president Robert Zimmer said landing the Obama Center is a “watershed moment for Chicago’s South Side,” at a euphoric news conference at the Gary Comer Youth Center, 7200 S. Ingleside. He was joined by Barack Obama Foundation chair Marty Nesbitt and Mayor Rahm Emanuel, among others.

“The Barack Obama Presidential Center will be unlike any that has come before it. It will be the first, truly urban presidential library located in the heart of a great global city simultaneously deeply connected to and engaged with the community and with programs of global impact,” Zimmer said.

RELATED:

SOUTH SIDE: Local residents happy it’s official
STEINBERG: Library, like Chicago casino, could be years away
LIVE UPDATES: Emanuel, foundation press conference on Obama library in Chicago

Reflecting on the four-way competition the foundation ran, Nesbitt said at a press conference Tuesday afternoon: “Ultimately, Barack and Michelle decided to return to their roots on the city’s South Side — the same streets where a young community organizer once inspired his community to take action.”

A decision on whether the center will be in Jackson Park or Washington Park could be made in six to nine months. Soil analysis and traffic and groundwater studies and other tests must be conducted in the parks, Nesbitt said. An architect won’t be picked for months. The center could open by 2020 or 2021.

The foundation and the Obamas made a sort of split decision, with post-presidential outposts planned in Chicago, New York and Hawaii.

Chicago’s South Side won the main prize — the massive Obama center.

The University of Illinois at Chicago, which was promoting West Side locations, got the least: a pledge of some sort of “collaboration,” the nature of which has to be determined.

Nesbitt said the foundation will establish a “presence” at Columbia University in New York and is “committing to spending time” there to work on potential long-term collaborations. Obama picked up an undergraduate degree from Columbia.

The University of Hawaii in Honolulu will get a sort of satellite center.

The Obama center will not only bring a historic institution to the South Side — the 14th presidential library in the federal system — it could potentially trigger an economic revival.

“Welcome home to Chicago’s iconic black Metropolis,” Carol Adams, the former president and CEO of the DuSable Museum of African American History, said at the press conference.

WATCH THE PRESS CONFERENCE

The South Side is “a community overflowing with assets yet also in need of the catalytic engine the Obama Presidential Center will surely be,” she said.

Chicago’s South Side, rich in African-American history, is “a community that despite its storied past now suffers the effects of systematic neglect and disinvestment,” she said.

Under federal law, the foundation has the job of raising the hundreds of millions of dollars it will take to build the structure and secure a significant endowment to operate the center.

It’s not clear how the cash-strapped city will pay for transportation and infrastructure improvements Emanuel has promised to make either Washington Park or Jackson Park more attractive and accessible.

“We will continue to make the investments necessary so whatever site is selected, it has investments in that area so everybody from the globe can get there conveniently,” Emanuel said.

Emanuel, Obama’s former chief of staff, responded with sarcasm when asked how those infrastructure projects would be funded when the city and state are struggling with billions in unfunded pension liabilities.

Then, he said, “Seriously, that’s putting the cart in front of the horse. Once a site is selected, I have all the confidence that — as a state, a city, a community and a university — we are gonna come together because this is a unique investment. . . . We will work together.”

The Obamas were sitting side by side in a video released at 5 a.m. on Tuesday. They both talked about the South Side.

“With a library and a foundation on the South Side of Chicago, not only will we be able to encourage and effect change locally, but what we can also do is to attract the world to Chicago,” Obama said in the video.

Michelle Obama said: “Every value, every memory, every important relationship to me exists in Chicago. I consider myself a South Sider.”

Obama launched his political career on the South Side. Michelle Obama was raised there, and they made their home near the U. of Chicago — first in a Hyde Park condo and then a Kenwood mansion

The video was shot on April 28, a source said. Nesbitt said he did not make a “formal recommendation” to the Obamas until Gov. Bruce Rauner signed a bill on May 1 reducing the threat of a lawsuit over the use of Chicago parkland for a presidential library.