DALLAS — As Mark Reuss, General Motors’ North America president, entered his first State Fair of Texas, he could see what GM is up against in a crucial battleground state for full-size pickup sales.He drove past Toyota’s truck display, where a Tundra dangled 50 feet overhead; a mechanical bull situated among Chrysler’s Ram pickups with banners boasting the Truck of Texas award; and finally a towering oil derrick with a Ford F-Series spinning atop with decals reading “Best selling truck” and “36 years running.”“Everybody drives pickups and loves pickups here,” Reuss said Thursday at the fair. “It feels bigger than life, and it is.”GM, which hadn’t redesigned its pickups since 2006, has seen the combined share for its Chevrolet Silverado and GMC Sierra slip to 33 percent in the Texas half-ton truck market last year from 36 percent in 2008, according to researcher Polk.That puts it behind Ford’s F-Series, the national leader and 2012 top-seller in Texas with 38 percent of the state’s market. Reuss said GM, which revealed its new heavy-duty trucks last week, can overtake Ford in Texas. The regular half-ton pickups, all new this year, began arriving in showrooms in May.“We’ve got the newest truck in the market. It’s been a long time since General Motors had the newest truck,” Reuss said. “The opinion and recognition of the how good the truck is starts in Texas. If we can win here with a great truck, there are ripple effects here across the whole country.”Texas is the nation’s largest market for new pickups, which represent 1 in five 5 vehicles sold in the state last year, according to Polk. It’s about 1 in 8 nationally. More large pickups were bought in Texas last year than the total for the next three largest truck markets: California, Oklahoma and Florida.“There’s more at stake in Texas in terms of volume and opportunities,” said Jessica Caldwell, an analyst with Edmunds.com, a Santa Monica, Calif.-based website that tracks auto sales. “It’s looking like it’s shaping up to be quite the battle between the players.”Ford’s display At Ford’s 300,000-square-foot display at the fairgrounds, a billboard boasts, “We own work.” A nearby stadium-appropriate video screen ticked off new F-Series sales under a headline that read: “Every 42 seconds, another F-Series is sold.” Ford executives wore black polo shirts and khaki-colored pants.“Suits really don’t fit at the State Fair,” Joe Hinrichs, Ford president for the Americas, said in an interview after Ford’s presentation for the 2015 Ford F-Series Super Duty and King Ranch heavy-duty version. He said Texas is the only state fair where he speaks.During his presentation, Hinrichs didn’t miss an opportunity to highlight Ford’s success in Texas. He told the crowd that Ford had delivered its 33 millionth F-Series this year at Sam Pack’s Five Star Ford in Plano.A recovering economy, new-housing starts and pent-up demand are driving demand for pickups, he said.“The energy sector, agriculture sector — all of these are big drivers of what’s driving the truck market in volume, especially right here in Texas,” he said.GM is bringing out a new high-end version of the Silverado called the High Country in the fourth quarter to better compete against Ford’s King Ranch. The High Country moniker is embroidered into the head rests of the heated-and-cooled bucket seats. Tom Peters, head designer for the trucks, estimated that the High Country has about 25 percent more chrome on the outside than the base Silverado.On Thursday at the fair, GM revealed new heavy-duty versions of its Silverado and Sierra pickups that are set to reach U.S. showrooms in the first quarter.Chevy has 42 events planned in Texas for the Silverado, which is about 33 percent of the 126 planned by year’s end. GMC has 11 of its 23 planned for Texas, according to GM.