The same way Johnny Unitas isn't associated with the city of Indianapolis but Baltimore, even though the Colts haven't been in Baltimore in over 30 years.
Earl Campbell IS Houston, Texas. He is the greatest football player to have ever played in this city and save for a debilitating genetic disease that affected his spinal cord he would have been even better than Jim Brown who has said Earl is the second best running back in the history of the NFL, after him (ever the modest one). The man's 1980 season is simply one of the greatest seasons in the NFL ever. He ran for over 200 yards FOUR times in one season and nearly eclipsed 2,000 in 15 games which is something only Eric Dickerson did and OJ Simpson (in 14).
Houston should never forget its sports past and Earl Campbell is part of its Mt. Rushmore.