Access to large data sets, including geographic information systems (GIS), provides teachers and students an opportunity to investigate policies of the past and their impact on people's lives. Students now have access to these digital resources through a variety of virtual, online collections, including the Library of Congress. Using a combination of statistical and geographic tools, students can examine maps as historical sources. This article introduces a classroom-based project--"Meaning in Maps"--that encourages students to critically examine maps from various historical periods. In the initial phases of the instructional unit the article describes students focus on two sets of historical digital maps: Sanborn Time Series maps and the maps produced by Federal Home Owners' Loan Corporation. An important theme that emerges for students is a more critical perspective on the economic and governmental policies that perpetuate inequality.