The National Climatic Data Center is nearing completion of a project to key the pre-1948 U.S. daily cooperative data. For the first time, all of these data, dating back to the 1890s, will be in digital form. Another project to quality control these data is just beginning. Because of these efforts, it will be possible to do a comprehensive analysis of variability and trends in short-duration (days to weeks) extreme events encompassing the entire U.S. and spanning the entire 20th Century. Prior to this time, such analyses have been limited in terms of spatial coverage and/or temporal extent. This paper presents a preliminary analysis of variability and trends. A subset of stations with very long records will be selected. The analyses will focus on multi-day episodes of extreme heat, extreme cold, and heavy precipitation. The spatial and temporal behavior will be described and discussed in the context of GCM projections of climate change.