On August 3, 2003, at 1930 central daylight time, a Cessna 172M, N73660, collided with a ditch and a road during an overrun landing on a 2,000 foot long grass private airstrip in La Monte, Missouri. The pilot and passenger were not injured. The airplane was substantially damaged. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The flight originated from Sedalia, Missouri, at 1900. The pilot stated he landed long with too much airspeed. The airplane continued off the end of the runway, through a wire fence, and across a ditch coming to rest on a highway. The pilot stated he exited the airplane and moved it to the side of the highway. The pilot reported that he was not very familiar with the landing strip and that he should have flown over the airstrip to check out its condition. He stated the grass was dry with some dead spots that did not offer any resistance during the landing roll.