With about 100,000 motorcycle riders about to converge on Washington this weekend for the annual Rolling Thunder tribute to veterans, an annual report released Tuesday shows no reduction in the number of riders killed in crashes.

Highway safety advocates have celebrated the steady decline in overall fatalities nationwide in the past few years, but the latest data show that the number of motorcycle fatalities remained about the same in 2011.

“It is disappointing that we’re not making progress in motorcycle safety, particularly as fatalities involving other motorists continue to decline,” said Troy Costales, chairman of the Governors Highway Safety Association (GHSA).

Although motorcycle deaths declined in 23 states in the first nine months of last year, they went up in 26 other states. Maryland saw 13 fewer deaths, Virginia had nine more and the District had two more than during the same period in 2010.

The decline in overall fatalities noted in a report by the GHSA, an organization of state highway safety officials, mostly reflects advances in four-wheel vehicles. The overall decline in deaths since 2005 has been attributed, in part, to air bags, seat belt use and vehicle stabilization.

Although detailed breakdowns weren’t available on the cause of accidents that killed 3,580 motorcyclists in the first nine months of last year, the GHSA drew on earlier years in pointing to three factors contributing to stubbornly high motorcycle fatalities — not wearing a helmet, alcohol consumption and speed.

“The good news is that we know how to prevent crashes. With so many motorcyclists on the road this month,” Costales said, noting the Rolling Thunder weekend, “it’s an opportune time to remind motorists about this critical highway safety issue.”

While some riders oppose mandatory helmet laws, the GHSA said 822 people would have survived crashes in 2008 if they had been wearing helmets.

Nineteen states, including Maryland and Virginia, and the District require all motorcyclists to wear helmets. Thirty-one states that once required helmets for all riders later repealed the laws, reducing to certain categories of riders, usually those younger than 21 or 18, the mandatory requirement. In three states, Illinois, Iowa and New Hampshire, no riders are required to wear helmets.

The GHSA report also pointed out that in 2010, 28 percent of those who died were riding drunk. And the most recent crash data show that 35 percent of those who died were speeding.

The motorcycle fatality rate rose steadily for nearly a dozen years, setting a record of 5,290 in 2008 before dropping dramatically the following year. In the 10 years ending in 2007, federal statistics showed the number of fatalities rose from 2,116 to 5,154, and the number of injuries almost doubled, reaching 103,000.

There was no ready explanation for the 16 percent decline in the first nine months of 2009.

The GHSA projected that once all the motorcycle deaths in 2011 are tabulated, the total will be about 4,500.

In soliciting the data in the report released Tuesday, the GHSA also asked state safety agencies to articulate the reasons for their state’s performance.

Virginia attributed its increase in motorcycle fatalities to “good weather conditions which resulted in a longer riding season.” Maryland simply noted, “We are back to where we were in 2004 prior to the bike boom.”

Several states that saw decreases — including Michigan, Ohio, Oregon and Wisconsin — said bad or rainy weather kept motorcyclists off the road.

Some states said it was a reflection of the number of new motorcycles being registered, with Nebraska reporting a significant increase in registrations while Wisconsin saw a 12 percent drop.