BAR HARBOR, Maine — Governors from six New England states and provincial leaders from eastern Canada discussed Tuesday how they might work together to improve regional transportation, energy generation and transmission, and economies.

Coming up with a uniform weight limit for trucks, pursuing renewable energy projects, increasing cross-border transmission capabilities, and boosting the region’s economy despite a declining population were among the topics tackled by the state and provincial officials.

During the morning part of the daylong New England Governors and Eastern Canadian Premiers Conference, officials cited the disparate weight limits between the two countries and among the New England states as a hindrance to economic growth.

In Maine, truck weights on Interstate 95 are limited to 100,000 pounds south of Augusta but they are limited to 80,000 north of the state capital. In Canada, trucks can travel with two trailers on the federal highway system and can carry more than 137,500 pounds. This disparity complicates traffic patterns by forcing heavy trucks to take circuitous routes through northern New England as they travel from the Maritime Provinces to southern New England or west to Quebec.

Maine Gov. John Baldacci and Vermont Gov. James Douglas each lamented the effect the truck weight limits have on the region, but not just on its economy. Baldacci said that though safety advocacy groups claim the limits make highway travel safer, they actually make it “more dangerous” on the secondary roads and in the small towns where the heavier trucks are forced to go.

Douglas agreed that one truck weight limit for the entire region would be good for the economy and for public safety.

“It’s been so frustrating for our state,” Douglas said. “It’s been environmentally detrimental to our state by forcing trucks to go through our small towns. We need to get some effort to get uniformity.”

Glen Weisbrod of Economic Development Research Group, who helped manage a recent transportation study of the two-nation region, told the elected executives about possible improvement projects that could make it easier for vehicles and goods to move in and through the states and provinces. There are several highways that run north and south through the region, but not so many that run east and west, he said.

By not improving the transportation network, by 2020 there could be “scary” bottle-necks in metropolitan areas such as Boston and New York, where many of the north-south highways converge, according to Weisbrod. He said that the projects that have been suggested, which include an east-west highway through northern Maine, could have a total cost of between $5 billion and $8 billion.

“It’s good chunk of money, but the benefits are three-to-one for the region,” Weisbrod said.

Greg Nadeau, deputy commissioner of policy, planning and communications for the Maine Department of Transportation, told the officials that states and provinces will have to try some innovative funding methods to come up with that kind of investment money. Maine has relied on motor fuel taxes to fund its road improvements, he said, but because escalating fuel prices are causing motorists to drive less, using fuel taxes alone will not generate the kind of revenue needed for transportation infrastructure projects.

Nadeau cited the seasonal Island Explorer bus system on Mount Desert Island as an example of how transportation projects can be funded from new sources. Twenty entities, many of them government agencies at different levels, help fund the free bus system, but much of its money is provided by outdoor retailer L.L. Bean, he said, which has contributed more than $1 million to the system’s costs.

“How it was funded had to be innovative, particularly in sight of the realities of the financial burdens on state and local governments,” Nadeau said.

When it comes to other aspects of the existing transportation system, Jean Charest, premier of Quebec, spoke up about how the participating states and provinces can help mitigate the effect of automotive emissions on the environment.

Charest said his province supports adopting emissions standards that have been championed and implemented in California, which has set a goal of reducing tailpipe greenhouse gas emissions by 30 percent within the next eight years. Last year, automobile manufacturers unsuccessfully sued the state of California, which voted in 2002 to adopt the standards. The manufacturers argued that the state law should be pre-empted by federal regulations and United States foreign policy.

Charest encouraged his fellow premiers and the New England governors to endorse the same standards and to inform their respective federal governments of that support.

“In Quebec, we have taken the position that we support California standards, [but] we’ve never said we will do it alone,” Charest said. “As far as I know, we would be the first region to speak to that.”

Charest also said that he supports pursuing a cap-and-trade approach to limiting the amount of automotive emissions into the atmosphere. By such a system, some polluters could acquire the rights to create more emissions than others as long as the total amount of emissions by all polluters did not pass a certain limit.

Connecticut Gov. Jodi Rell, Nova Scotia Premier Rodney MacDonald, Vermont Gov. Douglas, Rhode Island Gov. Donald Carcieri and Baldacci each indicated later in the day that they also support implementing the California tailpipe standards throughout North America as much as possible.

In a similar vein, the officials also heard about environmentally friendly energy projects that are being pursued in the region. Quebec has spearheaded many hydroelectric and wind power projects over the years, but other states and provinces are beginning to catch up.

Several thousand megawatts of renewable energy sources likely will come online in the region in the coming decades, according to Christian Brosseau of Hydro Quebec USA, including wind power projects in Maine. But transmission capacity also needs to be enhanced, both for electricity and natural gas, if the new sources of energy are to meet the region’s needs, industry officials said.

Baldacci said later that Maine could miss out on the benefits of these new energy projects if it withdraws from ISO New England, the operator of the New England regional power grid.

He said Maine Public Utilities Commission is studying the issue to weigh the pluses and minuses of being part of the electric entity. Proponents of withdrawal from ISO New England have said that Maine residents pay more than they should of the regional power rates.

Whatever is decided, Baldacci said, the state will work with its neighbors to make sure that Maine residents and the surrounding states and provinces benefit from regional energy projects as much as possible. He said Tuesday’s talks make him optimistic that Maine will be able to continue working with its neighbors going forward.

“We can’t do everything all by ourselves,” he said. “We’re part of New England. We’re part of this region. I’m encouraged, we’re not at the end of the road yet, but we’ll wait and see what happens.”

Premier Robert Ghiz of Prince Edward Island was not at Tuesday’s conference because he had to attend a funeral for former PEI Premier Bennett Campbell, according to New Brunswick Premier Shawn Graham. Campbell, who had cancer, died Sept. 11 at age 65 from complications of cancer.

George Webster, PEI’s environment minister, attended the conference on Ghiz’s behalf, taking his place among the other premiers and governors seated at the large central table set up in the Bar Harbor Club’s main ballroom.

Next year’s conference is scheduled for Sept. 15-17 in Saint John, New Brunswick.