The question of the value or relevance of regional seismic networks to the siting of critical facilities is valid given the Jack of a direct relationship between a cataloging of earthquakes and the critical questions of engineering design and confidence. A history of seismological knowledge of the central United States is presented. This history points out both what a seismic network is and is not capable of providing over a short period. Besides providing accurate locations and magnitudes of regional earthquakes, important by-products of the network support have been found--the most important of which, in the engineering sense, is the realization that the attenuation of strong ground motion is regionally frequency dependent, so much so that western U.S. strong ground motion spectra are not appropriate to the central and eastern U.S. An answer to the question whether or not regional networks are relevant is a qualified “yes”. Regional networks are relevant if they are part of a research program which addresses all aspects of the earthquake problem, from the acquisition of data to, most importantly, the use of that data to address the immediate needs of the engineering and regulatory communities.