Washington ? Only 52 of the nation’s 91,000 public schools are labeled persistently dangerous by their states, findings that allow students in those few schools to transfer to safer places but deny a similar option for tens of millions of other children.

Schools not on the list are not necessarily crime-free. There were nearly 700,000 violent crimes in America’s schools in 2000, the last year for which government numbers were available.

The new school year marks the first time that states must define and identify their most dangerous schools and let all students at those schools enroll elsewhere in their district. Most states have responded by declaring they have no schools fitting that description.

Forty-four states, including Kansas, and the District of Columbia reported not a single unsafe school. The exceptions were Pennsylvania (28), Nevada (eight), New Jersey (seven), Texas (six), New York (two) and Oregon (one). The numbers may change after final state reviews or appeals.

At a time when campuses use a range of tools to halt crime, from metal detectors to full-time police officer, 99.9 percent of schools got passing safety grades, based on self-reported data.

“I don’t think most parents would be surprised to find out that schools aren’t persistently dangerous because they believe their schools are safe,” said Jo Loss, mother of two public-school children in Castro Valley, Calif., and a leader of the state’s PTA.

The order to designate unsafe schools is part of the No Child Left Behind federal law designed to hold schools accountable and give students choices. But to some school advocates, the small number identified is so implausible it renders the ordered assessment meaningless.

“The states are sending a false sense of security to parents, and it creates a laxity among educators in terms of school safety,” said Kenneth Trump, a national school safety consultant who has worked with officials in more than 35 states. “It’s like a government Grade A stamp of approval saying everything is safe and fine.”

To get the label in Washington state, for example, a 1,000-student school would have to expel three students per year for gun violations and 10 additional students per year for other violent offenses — and that would have to happen for three straight years.

Washington’s policy was purposely set high because of the “significant consequences of being defined as persistently dangerous,” said Martin Mueller of the state’s Office of the Superintendent of Public Instruction.

Connecticut gives schools three years to fix problems.

“If they do not improve, then they can be named, but we are not automatically condemning a school,” said Thomas Murphy of the state’s Education Department.

Most states have determined that to merit the dangerous label, schools must meet at least one threshold, such as student gun violations or expulsions based on violent behavior.

Typically, states tied the minimum number of incidents to enrollment — requiring a higher number at larger schools — and they only count schools that show trouble over two years or three years.

The states also based their definitions on the most serious crimes: murder, arson, robbery, kidnapping. A dangerous environment, not just unacceptable behavior, is the target, said Bill Modzeleski, school safety director for the Education Department.

“When you see what Congress said in the legislation, then clearly there probably aren’t as many persistently dangerous schools as the public may believe,” he said.