(FORTUNE Magazine) – As companies decentralize, headquarters aren't what they used to be -- but they're still the corporate nerve center. Got something to sell, need more information, want to complain? We give you the address, the phone number, and the CEO's name. Service companies tend to be spread a bit more widely than industrials, but the same three states still head each list; one-third of the service crowd resides in them. The shift to the Sunbelt continues, if slowly. This year only one company made the switch: Southwestern Bell, from St. Louis to San Antonio. And there are always patterns to discern. Arkansas, for example, newly prominent on the national scene, is home to six of the Service 500, three of which are major trucking companies. Maybe mobility is a cultural trait in the ''Land of Opportunity.''

CHART: NOT AVAILABLE CREDIT: NO CREDIT CAPTION: THE SERVICE 500 WITHIN THE STATES