The geographically proximate firms are those located in the same 3-digit zip code
as firm i.
Private insurance fees for the 84 selected physician services were obtained from the PHCS 1990 national data base that, as noted, reports fees for 3-digit ZIP Code
Means CostWorks Square Foot cost module provides access to 70 commercial building types that can be tailored through modifications of key parameters, extended with common additives, localized to any 3-digit ZIP code
in the United States and reported with detail by building elements to reflect actual project requirements.
Nationally, there are 770 3-digit ZIP Code
areas, compared with more than 3,000 counties.
Some of the most popular territories that companies use are:US States, zip codes by State, counties by State, PUMA territories, and 3-digit zip codes