General Order 64-A
Section II
Definitions Of Terms Used In This Order
20.9 Districts mean urban, rural or loading, as defined in the following definitions:
A. Urban Districts mean thickly settled areas (whether in cities or suburbs) or where congested traffic often occurs. Highways on which traffic is often very heavy or locations such as picnic grounds, summer resorts, etc., where people congregate seasonally, are considered urban.
B. Rural District mean all places not urban, usually in the country, but in some cases within city limits.
C. Loading District mean those areas in which the specified loadings of Rule 43 shall apply. They are known as “Heavy” and “Light” loading districts, and unless the United States Weather Reports indicate differently, the former shall be that territory 3000 feet or more above sea level and the latter shall be that territory below 3000 feet.