By Jonathan Allen

NEW YORK (Reuters) - A Bronx jury cleared bus driver Ophadell Williams of all counts except unlicensed driving in a crash that killed 15 passengers returning to New York's Chinatown from a Connecticut gambling outing.

Jurors rejected 53 counts against Williams, including manslaughter, criminally negligent homicide, assault and reckless driving. He was convicted of a single count of third-degree aggravated unlicensed operation of a motor vehicle.

After a lengthy trial marked by delays, the jury's verdict, reached on Thursday during its second week of deliberations, was read on Friday. Judge Troy Webber had ordered the verdict sealed overnight because one juror had an appointment.

The horrific predawn crash on Interstate 95 in March 2011 triggered a federal and state crackdown on bus operators, including proposals to fit vehicles with speed-limiting devices and to require companies to get 10 years of driving records from potential employees.

Prosecutors said Williams, 41, of Brooklyn, whose driving record included 18 suspensions over two decades, was tired when his speeding bus hit a guardrail, flipped onto its side and skidded into a highway sign pole, shearing off the roof. Of 32 passengers, 15 died and 15 were injured, some severely.

The bus was returning passengers to Chinatown after a night of gambling at the Mohegan Sun casino in Connecticut.

Williams' trial, which was interrupted by Hurricane Sandy, was followed by drawn-out jury deliberations that were marked by juror absences and other scheduling glitches.

The judge's decision to seal the verdict overnight to accommodate a juror's scheduling conflict surprised lawyers in the case.

It also left Williams, who had to return to jail to await the verdit, "very, very frustrated," defense lawyer Patrick Bruno said on Thursday.

(Reporting by Jonathan Allen; Editing by Barbara Goldberg and Doina Chiacu)