PROVIDENCE — While Rhode Island residents are the most frequent visitors to their home-state slot parlors, close to 40 percent of the gambling-related dollars that went into the state treasury last year from Twin River and Newport Grand — an estimated $117.4 million — came from Massachusetts residents crossing into Rhode Island to try their luck.

That was among the findings of the 2009 edition of the New England Casino Gaming study issued annually by the Center for Policy Analysis at UMass-Dartmouth. Under the guidance of its director, Clyde W. Barrow, the center a month ago conducted a poll for Northeast Resorts, a company with options on 35 acres in New Bedford’s Hicks-Logan neighborhood, near the city’s waterfront, that hopes to build a casino there. The poll findings: a narrow majority — 51 percent — would favor a casino on the New Bedford waterfront.

While Barrow’s latest report does not directly pit one state’s ambitions in the gambling arena against the financial well-being of another, it illustrates the extent to which Rhode Island is dependent on out-of-state gamblers to feed the state treasury here and potentially vulnerable, as a consequence, to any of the proposed moves in Massachusetts to allow full-scale casinos or slots at its tracks.

Among the findings and conclusions: only four casinos and “racinos” in the United States have more slot machines than the 4,752 at the upgraded greyhound racetrack in Lincoln and they are: Foxwoods, 8,104; Mohegan Sun, 6,761; Empire State Raceway 5,334; and Bally’s Atlantic City 4,786.

Twin River’s owners spent upwards of $220 million on renovations after buying the former Lincoln Park greyhound racetrack, a huge investment they have been struggling to pay after defaulting last March on loan payments to a group of lenders led by the Merrill Lynch Capital Corp.

“According to Twin River officials, the improvement, expansion and rebranding of the former Lincoln Park was designed to extend its market gravity from a 30-mile radius to a 60-mile radius, which would allow it to draw larger numbers of patrons from the Worcester and Boston markets,” the Barrow report said.

While this strategy was “moderately successful,” last year’s study “also found signs that one element of Twin River’s 2007 success story was its cannibalization of the Newport Grand slot parlor.” This year’s updated study found: “Twin River has put a small dent in the flow of gamblers from Rhode Island to Connecticut, but it remains primarily a convenience gambling facility that attracts local gamblers from Rhode Island, Southeastern Massachusetts and central Massachusetts.”

Despite Twin River’s much publicized problems with its lenders and creditors, the report said, its 2006-07 expansion “positioned [it] to withstand the current recession better than many gaming facilities throughout the country.” After a strong start, it ended calendar year 2008 up by close to 6.5 percent, despite a difficult second half.

By way of comparison, Newport Grand’s video-slot revenue was down an estimated 7.1 percent during the same period, according to the study, which said this marked the fourth consecutive year-to-year revenues decline for the former jai alai fronton, “mainly due to a decline in its Massachusetts customer base or the diversion of a portion of its Massachusetts customer base to Twin River.”

In 2008, Rhode Island residents spent an estimated $250.9 million at Foxwoods and Mohegan Sun, which is an estimated $40.7 million less than they spent at the two Connecticut casinos two years earlier.

The report out yesterday notes that state Rep. William San Bento, the new chairman of the Rhode Island General Assembly’s Lottery Oversight Commission, has introduced a bill to give voters a chance to amend the state Constitution to allow full-scale casino gambling at Twin River and Newport Grand. No hearings have been scheduled as of yet on the legislation, which was co-signed by 24 of the 75 House members.

Asked if Twin River had any comment on the UMass-Dartmouth report, spokeswoman Patti Doyle said: “We have not had the opportunity to read the 60-page report in its entirety. However, we are and have been focused exclusively on creating a first-class entertainment and gaming experience for our customers from Rhode Island and nearby Massachusetts and will continue to do so.” Newport Grand CEO Diane Hurley said she had not read it.

At an oversight commission meeting yesterday, state Lottery director Gerald Aubin said the year-over-year losses have moderated after peaking at 15 percent in Lincoln, 21 percent in Newport. During the week that ended March 14, Twin River was down only 5 percent compared with the same point a year ago, and Newport Grand 7 percent.

kgregg@projo.com