Question: When did the last season of one tree hill air?
Disambiguated questions and answers: question: When did the last season of one tree hill begin to air?
When did the last season of one tree hill finish airing?
Over what span did the last season of one tree hill air?
answer: January 11, 2012
April 4, 2012
January 11 – April 4, 2012
Natural Questions answer: January 11 , 2012 (from the Wikipedia article "One Tree Hill (season 9)")