Demand for electricity increased. The first pie chart shows the 1999 summer peak demand by each of the four subregions of the Western Interconnection. The second pie chart shows where peak demand growth occurred from 1995 to 1999. (Source: Northwest Power Planning Council)

Summer Peak Demand and Demand Growth in the West

WSCC Regions: Northwest (I); Rocky Mountain (II); Arizona-New Mexico (III); California-Mexico (IV):