This raster dataset is a georeferenced image of "Proposed Southern Crossings of San Francisco Bay," originally contained in the "Report to Department of Public Works on the southern crossing of San Francisco Bay," This report was originally created by the California Division of Bay Toll Crossings in October 1956. A scanned version of this map was georeferenced as part of the Imagined San Francisco project. This project traces the history of urban planning in San Francisco, placing special emphasis on unrealized schemes. Rather than using visual material simply to illustrate outcomes, Imagined San Francisco uses historical plans, maps, architectural renderings, and photographs to show what might have been. By enabling users to layer a series of urban plans, the project presents the city not only as a sequence of material changes, but also as a contingent process and a battleground for political power. Savvy institutional actors--like banks, developers, and many public officials--understood that in some cases to clearly articulate their interests would be to invite challenges. That means that textual sources like newspapers and municipal reports are limited in what they can tell researchers about the shape of political power. Urban plans, however, often speak volumes about interests and dynamics upon which textual sources remain silent. Mortgage lenders, for example, apparently thought it unwise to state that they wished to see a poor neighborhood cleared, to be replaced with a freeway onramp. Yet visual analysis of planning proposals makes that interest plain. So in the process of showing how the city might have looked, Imagined San Francisco also shows how political power actually was negotiated and exercised. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.