The pilot reported that, during preflight preparations, he filled the fuel tanks with 50 gallons total fuel and planned to switch between the fuel tanks 1 hour and then 3 hours into the flight. He stated that each fuel tank contained 24 gallons of usable fuel and that the estimated fuel burn was 10 gallons per hour. He departed with the fuel selector on the right fuel tank. One hour into the flight, he switched to the left fuel tank. The pilot stated that, while descending to land at the destination airport, about 3 hours 10 minutes into the flight, he set the mixture to full rich and turned on the fuel pump, and the engine "immediately lost power." He then began an emergency checklist, turned on the carburetor heat, and cycled the fuel pump and throttle, but the engine did not respond. Subsequently, he conducted an off-airport landing on a road. Upon landing, the right wing impacted brush and weeds, and the airplane then veered right and came to rest in a ditch. The airplane sustained substantial damage to the right wing. A Federal Aviation Administrator inspector reported that the fuel selector valve was set to the left fuel tank. The propeller and engine cowl sustained minimal damage, and no fuel was found in the engine fuel sump. The left wing appeared undamaged, and less than 1 quart of fuel was found in the tank. The right wing exhibited extensive aft crushing damage to the outboard leading edge, and the fuel line was crimped and broken by impact forces, and no fuel was found in the fuel tank. The airplane manufacturer's Pilot's Operating Handbook (POH), Chapter 3.3, "EMERGENCY PROCEDURES CHECKLIST," contained an Engine Power Loss During Flight checklist, which stated, in part, the following: Fuel selector: switch to tank containing fuel Electric fuel pump: ON Mixture: RICH Carburetor heat: ON Engine gauges: check for indication of cause of power loss Primer: check locked. If no fuel pressure is indicated check tank selector position to be sure it is on a tank containing fuel. Although no fuel was found in the right fuel tank, this was likely due to the break in the fuel line caused by impact forces. Given the fuel burn rate and the length of the flight, the right tank likely had sufficient fuel onboard for flight, and the pilot's failure to move the fuel selector to the right tank, as called for in the POH, likely led to fuel starvation and the subsequent loss of all engine power.