Report details forecast of convention spending

Delegates to the upcoming Democratic National Convention will spend $30 million at local restaurants and stores, $27.3 million on hotel rooms, and $4.3 million on transportation, according to a detailed economic analysis by Mayor Thomas M. Menino's budget staff and other local economists.

The study, which has been used by Menino and other convention boosters to highlight an estimated $154.2 million economic boon from the convention for months, was released to the public yesterday, allowing the first detailed accounting of how that estimate was formulated and where all the dollars are expected to go.

Total direct spending from conventioneers is pegged in the report at $126.1 million, including millions of dollars in wages for local workers and revenues for shops in Suffolk County, which includes Boston, and the four surrounding counties.

But the study does not factor in potential economic losses to the region from closing the Central Artery and North Station, key routes into downtown Boston for thousands of workers and shoppers, for the entire convention week. It does, though, show how some of the cash spent by delegates and convention organizers in Boston will end up trickling out of the city or out of Massachusetts entirely.

''Some of it will be spent in Boston and much of the rest of it will be spent outside of this area," said John Havens, associate director and senior research associate at Boston College's Social Welfare Research Institute. Havens worked on the study as an unpaid consultant.

''Some of it will be spent outside the Commonwealth. It's not that the city is going to lose spending, but not all the growth is going to occur in the city or stay here," he said.

''Surely, though, there will be costs. Estimating the scale of those costs is very difficult, if not impossible."

According to the report, the estimated 35,000 conventioneers will spend $104.7 million in Suffolk County, and $21.4 million in total spending in Norfolk, Middlesex, Essex, and Plymouth counties -- accounting for the $126.1 million direct spending figure.

The study's authors factored in an additional 22 cents in so-called ''multiplier effect" spending -- essentially the ripple effect of the new dollars generated from the convention -- for every dollar spent to arrive at the $154.2 million economic impact total.

But when that ripple effect is broken down between Suffolk -- where the convention will be held -- and the surrounding four counties, Suffolk's total of $82.8 million is actually $22.5 million less than the amount of direct spending expected to take place here, while the other counties see a $50.6 million boost.

Put another way, once direct convention spending is calculated, the dollars begin to flow out of the Boston area to the fringes of the region and beyond, where their long-term impact will continue to be felt long after the Democrats leave.

In an interview yesterday, Menino said it is important to view the convention as a regional economic generator, not just one for the city.

''You have to look at this as a region, not just the city," he said.

Outlying areas will likely see a greater ripple effect from the convention than Boston because hotels and restaurants there would not normally be as busy in July as those in the city, where tourist business booms in the summer, he said.

''Boston would be at a certain level normally because of hotel rooms. Their occupancy rates are going to be much higher, and the ones in the suburbs would be less busy."

Another factor economists said could affect the convention's economic value is the planned closure of the Central Artery and North Station during the convention. About 1 million commuters are expected to be delayed getting to work that week, including an estimated 200,000 drivers who will be detoured onto other, crowded roads and 24,000 subway and commuter rail riders who normally pass through North Station daily.

Economists said they could not quantify the potential economic damage of the closures and how they might affect the convention's net impact on Boston's economy without first doing a detailed study -- something no one has done yet. But, they said, it needs to be considered.

''Those are very important questions, but it's very difficult to estimate what the economic costs of the convention are in the same way that one could estimate the economic benefits," said Michael Goodman, director of economic and public policy research at the University of Massachusetts Donahue Institute.

Keith Reed can be reached at reed@globe.com.