If you're the kind of person who geeks out watching San Jose grow into the Bay Area's biggest city or zooming through the Hetch Hetchy Valley before it became San Francisco's water supply, you'll love the United States Geological Survey's new topoView.
In 1879, the USGS began mapping regions around the country. Now you can view thousands of old maps from the archive in an easy-to-use viewer. The tool also lets you download old maps in a variety of formats, including JPGs, KMZs and PDFs.
Below, we've taken topoView's oldest maps of San Francisco, San Jose and Oakland and matched them with current maps from CartoDB.
San Francisco: 1895 and 2015