By a two-to-one margin, Miami Beach voters gave the City Commission the authority to add up to a penny to the city’s resort tax to finance major improvements to the Miami Beach Convention Center.

The vote was pushed by Miami Beach’s hotel association and chamber of commerce and by North Bay Village Commissioner Stuart Blumberg, who chairs the convention center advisory board.

A one-cent increase to the resort tax could add about $9 million annually. The extra funds, which could be bonded out to as much as $90 million, would then be used exclusively to “expand, enlarge, renovate, and/or improve the convention center’’ and pay down debt associated with a major improvements project, according to the ballot language. After the project is paid off, any extra money would go into a fund for upkeep.

The convention center is generally regarded as Miami-Dade County’s third-largest economic engine behind the airport and seaport.

Business boosters pushing the referendum stress that a vote for a resort tax increase was a vote for improving the convention center and not an endorsement of the city’s 52-acre district project.

Voters also decided to allow a majority of the City Commission to call for a special meeting. Commissioners placed the issue on the ballot after four of the city’s seven elected officials unsuccessfully requested a special meeting in April following the FBI’s arrest of city code and fire inspectors on charges that they shook down a South Beach nightclub owner in exchange for favorable treatment. Only the mayor and city manager can call a special meeting, according to the city charter, and both refused, in part because the commissioners who called the meeting wanted to fire the manager.

In other ballot questions:

• North Miami voters narrowly rejected the expansion of the Museum of Contemporary Art, or MOCA, which would have been financed through a $15 million city bond issue. The proposed 27,000-square-foot expansion would have tripled the space.

The average homeowner would have seen a $48 increase in his annual tax bill to pay for the bond, said North Miami spokeswoman Pam Solomon.

But some were skeptical.

“We’re focusing on a cultural program that will cost us more than it will bring in,” North Miami resident Catherine Christofis said last month.

• Opa-locka voters rejected a charter amendment that would have had the city pay $7,500 a year into retirement plans for the mayor and city commissioners. The amendment would also have given commissioners leaving office after at least eight years some health and life insurance.

• Miami Springs voters chose to keep two-year terms for their commissioners by rejecting an amendment that would have extended the terms to four years. Miami Springs voters also rejected staggered terms for commissioners.

• Miami Gardens voters rejected an amendment that would have redrawn the lines for the four “residential areas,” essentially the City Council districts for four of the City Council members. Two City Council members are elected by the whole city. After the 2010 Census, the city found that the population of area 1 was significantly smaller than that of area 4, so a charter amendment was proposed to even out the areas.

Miami Herald staff writers Nadege Green and David Smiley contributed to this report.