TULSA, Oklahoma - Traffic backed up on Tulsa's Inner Dispersal Loop Friday morning as drivers headed to work encountered a number of street closures and detours in downtown area ahead of this weekend's Williams Route 66 Marathon. 

Tulsa Police worked several minor crashes including one involving a school bus on an IDL exit ramp at Detroit. A commercial van rear ended the school bus.

The City of Tulsa began closing streets for the marathon Thursday morning, but when drivers encountered closures on Martin Luther King Boulevard and several other downtown streets Friday morning, traffic slowed to a crawl into the downtown area.