Riding along on a historic cross-country adventure

After fixing his gaze on such epic areas of Americana as jazz, baseball and the Civil War, documentary wizard Ken Burns tonight tackles a topic far narrower in scope, yet countrywide in scale. It’s a story that begins May 19, 1903, with a wager in a San Francisco club and ends 10 weeks and 5,600 miles later in Manhattan, capping the first coast-to-coast journey via that newfangled contraption called the automobile.

But “Horatio’s Drive: America’s First Road Trip” (9 p.m., KCET) represented more than a $50 bet to Horatio Nelson Jackson, a wealthy 31-year-old physician whose early retirement left him hungering for new challenges. And his achievement was more than a headline-grabbing stunt: It helped grease the wheels for the nation’s imminent transition from horse power to horsepower.

In assembling the nearly two-hour documentary, Burns and writer/co-producer Dayton Duncan hit the road themselves, tracking the route taken by Jackson and 22-year-old mechanic Sewall K. Crocker a century earlier. The detail work by Burns and Duncan offers such an authentic-feeling trip back in time that it’s as if viewers have a backseat perch as Jackson puts his cherry-red Winton touring car in gear and heads east.

Jackson’s own photos from the journey, period music and an impressive array of archival material from the producers bring the trip to life, as do the heartfelt letters Jackson dutifully sends home along the way to wife Bertha, whom he affectionately calls “Swipes” (Tom Hanks voices his role). When obtaining food or gas wasn’t a problem, torrential downpours were, and when the sun was shining, the vehicle’s mechanics were failing. Yet through it all, Jackson maintains a ferocious optimism.

One flaw is pacing, with the narrative slowing and the accounts of the setbacks growing a tad repetitious as the adventurers get bogged down in Wyoming. But before long, everything’s moving again.

A final note: After succeeding in his quest, Jackson never bothered collecting on the $50 bet.