By age 23, almost a third of Americans have been arrested for a crime, according to a new study that researchers say is a measure of growing exposure to the criminal justice system in everyday life.

The study, the first since the 1960s to look at the arrest histories of a national sample of adolescents and young adults over time, found that 30.2 percent of the 23-year-olds who participated reported having been arrested for an offense other than a minor traffic violation.

That figure is significantly higher than the 22 percent found in a 1965 study that examined the same issue using different methods. The increase may be a reflection of the justice system becoming more punitive and more aggressive in its reach during the last half-century, the researchers said. Arrests for drug-related offenses, for example, have become far more common, as have zero-tolerance policies in schools.

The study did not look at racial or regional differences, but other research has found higher arrest rates for black men and for youths living in poor urban areas.