This article serves three purposes. First, we present a new source of campaign finance data for the 50 states. This includes annual data on candidate expenditures in gubernatorial races from 1977 to 2001, as well as triennial and biennial data on campaign finance laws affecting gubernatorial races during this period. Second, we review the various sources of campaign finance data for the 50 states. Third, we examine the challenges of collecting and compiling data across the 50 states, since these data can vary so much in availability and measurement. We hope to provide some general lessons to researchers collecting or working with all types of cross-state data.