Published by the American Geophysical Union as part of the Field Trip Guidebooks Series, Volume 181.Field Trip T181 is an overview of the geologic problems — and opportunities — associated wiht development of cities and towns in the western United States. The trip deals specifically with urban areas in the states of California, Nevada, Utah, and Colorado. Its route is an historic one, being followed by the European settlers moving west during the last century. Not coincidentally, it was also a route covered by the pioneering King, Hayden, and Powell geological surveys. These early expeditions were the immediate ancestors of the modern United States Geological Survey.