CLAYTON • The St. Louis County Council is set to vote next Tuesday on a proposal to commit $240 million over four decades for an expansion and upgrade to America’s Center in downtown St. Louis.

The council voted 6-1 on Tuesday to adopt a bill with three significant last-minute changes to the proposal, which has been on the council’s agenda for several weeks. A final vote on the revamped bill is set for next Tuesday, Council Chairman Sam Page said.

The county’s support would help finance a $175 million plan to expand and upgrade America’s Center. The measure’s supporters have said the project is needed to draw more conventions, allowing St. Louis to better compete with peers such as Indianapolis and Nashville, Tenn., which invested hundreds of millions of dollars to upgrade their tourism infrastructure. Some critics have said the county could use the money for other improvements.