Inside Report (7)

''Go West, young man!'' It took 100 years, but the US has finally taken Horace Greeley's advice.

For the first time, the center of US population is located west of the Mississippi River - in a wooded area just outside De Soto, Mo. The Census Bureau says the spot is where a rigid map of the US would balance if 226,545,805 equal weights were placed in the location representing each person on April 1, 1980.

Local reaction? Says Bazel E. Davis (manager of a hair-style shop on East Main Street) of the owner of the wooded lot, ''He's certainly cleaned that place up - since it's the center of the population.''