The teen drama is currently on its fifth run in the US but began as an underdog, with little promotion, on the WB channel. Executive producer Brian Robbins told Variety it struggled to survive.
"I remember the show premiered, and nobody watched it... I remember being in the editing room editing the next show (and saying), 'I'm sure they're going to be coming to take away the equipment any moment now, but let's just keep going.'"
In response creator Mark Schwahn and executive producer Joe Davola began a crusade of low-level promotion, sending actors to make public appearances across the US.
Warner Bros TV president Peter Roth said: "When we had our first mall tour, at that point we were flabbergasted by the extraordinary turnout of screaming, ardent, teenage fans of the show. There's an old adage in show business that attitude precedes behaviour. We saw that in that mall tour."
Other initiatives included a competition for a viewer's home town be used for a shoot and a successful concert tour sponsored by Sunkist.
Davola recalled: "Sales of Sunkist went up. They documented that that was due to being associated with One Tree Hill. We're in an advertising-based business - I think the network took notice of that."
Schwahn said another battle was convincing producer and channel bosses of his plan for the fifth season which was set some four years after the previous run. Roth admitted he was "fearful".