In a marathon meeting, the Prince George's County Council voted Wednesday to place a proposal on the November ballot that would allow elected officials to serve three terms instead of two; adopted a community benefit agreement with the MGM casino; and supported increased greenery in the county by requiring more trees to be planted.

On the last day before their summer recess, council members worked through a 25-page agenda before addressing the most controversial issues: term limits and the MGM deal.

County voters have previously rejected changing the policy limiting elected officials to two four-year terms, which was imposed 20 years ago after a grass-roots campaign by residents.

Prince George’s is the only jurisdiction in the D.C. area that has term limits, which some county officials say hampers their ability to move the county forward.

“We are always starting over,” said council member Andrea Harrison (D-Springdale), adding that as a member of the Metropolitan Washington Council of Governments, she has seen other jurisdictions build more successfully on long-term ideas because there is continuity among elected officials.

“Prince George’s County is the only [jurisdiction] with constant turnover,” she said. “We have to remember that we are competing and are at a regional disadvantage because of our term limits.”

Angela Holmes, president of the Prince George’s County Civic Federation, said that voters have already spoken — first when the policy was created and later by defeating other attempts to reverse it.

“Eight years should be enough” for a politician to serve, she told the council. “At the ninth year, new faces and new ideas are favorable.”

Some proponents of term limits say the proposal to allow politicians to serve three terms could be a precursor to abolishing the limits.

Holmes said and others who oppose extending the limit say they will conduct a public education campaign to make sure voters know the “repercussions” of modifying it.

“This is a difficult discussion to have when you’re talking about a move that seems self-serving,” council member Mary A. Lehman (D-Laurel) acknowledged. “But I think that there is a strong case to be made that eight years is not enough time to do the things that we are attempting to do here.”

The favorable vote on the MGM casino agreement did not come with objections. The community-benefit pact sets employment and contractual goals for the $925 million gambling resort, which is expected to open in 2016 at National Harbor.

Council member Obie Patterson (D-Fort Washington) said he spent Tuesday night researching the county’s bylaws to find a way out of voting in favor of an agreement that he thinks shortchanges the constituents of his district, which includes National Harbor.

“All I’m saying is, will we have done our job such that the citizen will benefit?” he asked. “[Or] will we have developed a platform for millionaires to become billionaires?”

Maryland awarded its sixth casino license to the Nevada-based company in December. After months of negotiations and planning, the council on Monday authorized construction to begin on the complex. The benefit deal was negotiated separately between the county executive’s office and MGM, stoking protest from some members of the community.

“I don’t know if you can compensate a community for intangible things like quality of life,” Lehman said. She said she is concerned that the state and county “do not have a handle” on the impact the casino will have on adjacent communities and the region as a whole.

Council member Eric Olson (D-College Park), who does not support gambling, said he sympathized with his colleagues’ reservations.

Council Chair Mel Franklin (D) pointed out that the agreement, in which MGM agreed to draw about 40 percent of its workers from among county residents, was the only one of its kind in the state. He praised the county officials who inked the deal, saying the project is likely to be fruitful for many years to come.

Before voting yes, Patterson said he will monitor whether MGM meets the specific goals for hiring county residents and minority-owned businesses to fill construction and casino jobs.

In other action, the council approved a “shade tree policy” that would increase the number of trees planted along county right-of-ways frequented by pedestrians, marking a stronger commitment by officials to strengthen and improve the suburb’s tree canopy.

Environmentalists across the region have been working with local governments to increase tree cover, saying it leads to better health for residents, reduces water and air pollution, and increases property values.

It’s also an issue of environmental justice, officials say. A recent study found a link between tree-lined, leafy neighborhoods and socioeconomic status. The lower the income of the residents, the sparser the tree cover, researchers said.

“If you look at satellite imagery, it definitely tells a story that the eastern side of the [Washington metropolitan] region does not have nearly the tree cover of the neighborhoods on the western side of the region,” Olson said.

Fewer trees means less absorption of storm-water runoff that can pollute waterways, lead to poorer air quality and reduce walkability. Trees also add to the community aesthetic.

The council will reconvene after Labor Day.