Boston police last year made 241 drunken driving arrests, or just two every three days, a sharp decline from recent years and far fewer than in cities of similar size, raising questions about how aggressively police are patrolling city roads.
Since 2009, in fact, arrests for impaired driving have fallen by one-third, to a total that pales in comparison with other jurisdictions. Denver, which has a slightly lower population, made more than 3,000 arrests last year. Police in Charlotte, N.C., a somewhat larger city in a smaller metro region, made nearly 1,600. Arrests in Philadelphia were nearly 20 times as high as Boston, according to arrest figures obtained by the Globe.