Money wagered at U.S. casinos rose at its slowest rate in more than a decade last year, as new casino openings slowed to a crawl and business dropped sharply in Nevada after Sept. 11, according to a report released on Wednesday.

Gamblers spent about $25.7 billion last year at casinos in the 11 states with legalized gambling, up from $24.5 billion in 2000, according to the American Gaming Association.

The 5 percent gain for the year was the lowest in a decade, and came in sharp contrast to the double-digit gains for seven of the last 10 years. Before 2001, the slowest growth was 6.9 percent posted in 1996.

“The overall gaming slowdown was obviously due to the disastrous terrorist attacks on Sept. 11 and the impact on the industry,” said Goldman Sachs analyst Steve Kent. “But there was also the fact we had no new markets opening up. Markets are generally maturing, and you can’t sustain the year-over-year gains without new markets opening up.”

Among the 11 legalized casino gambling states, Nevada led the pack with $9.5 billion in gross casino revenues — about 37 percent of the national total. New Jersey was second, with $4.3 billion, followed by Mississippi with $2.7 billion.

Other states generating $1 billion or more in revenues included Illinois, Indiana and Louisiana, each with $1.8 billion, Missouri ($1.1 billion) and Michigan ($1 billion). Iowa, Colorado and South Dakota are the three other states with legalized casino gambling.