From the Lawrence Daily Journal-World for July 19, 1971:

The nation’s chief tornado forecaster was concerned about the latest trends in home-building in the nation. “Half the single-unit new housing starts in the United States are mobile homes,” said Allen Pearson, head of the National Severe Storms Forecast Center in Kansas City. Pearson was concerned that the new mobile homes were “sitting ducks” for tornadoes and other wind storms. “Mobile homes are useful and necessary. The only problem is how to help those who own them to avoid becoming casualties…. There are about 700 tornadoes a year in this country, but we estimate that less than 100 of them are real blockbusters with winds of 200 or more miles an hour.” He went on to urge mobile-home residents to take the precaution of tying down their homes with steel cables and a clamp on the I-beam under the unit.