ST. LOUIS • Over the next three years, a sleek, square soccer stadium may rise out of highway ramps and empty fields west of Union Station downtown. Architects imagine sharp corners, open ends, public plazas and a clear canopy that reaches over the seats and amplifies the deafening game day roar.

The ownership group working to land a Major League Soccer team here has designed an open-air stadium with a natural-grass field 50 feet below street level, ringed by 22,000 seats in two tiers, according to the first renderings of the stadium to be publicly released. A wide, long awning of clear plastic architectural sheeting shelters the seats, keeping out weather, letting in light and holding in noise.

“This is the real deal,” said Carolyn Kindle Betz, one of the owners and the face of the group. “The ownership group is absolutely committed to getting this team.”

The release of the renderings, which Betz called conceptual, comes just days after MLS owners voted to expand the league by three teams to 30 and enter exclusive negotiations with the top two bids, in St. Louis and Sacramento, Calif.

The decision ended weeks of speculation on which city’s bid would win. The league had long said it would expand no further than 28 this year.