The David Rumsey Historical Map Collection is an Internet site featuring more than 6,500 high-resolution digital images from one of the largest private map collections in the U. S. Nineteenth and early 20th century maps, modern age aerial photos, satellite imagery and other raster-based data is accessible on the website. The mapping service enables Web browser interaction and visualization of 11 different historical maps of San Francisco Bay, from the mid-1800s through early-1900s, along with digital orthophotos, topographic map sheets, digital elevation models, and satellite imagery from the U. S. Geological Survey. Roads, lakes, parks, and state boundary data are also part of the service. The site will soon include historical maps of New York City, Boston, Los Angeles, Chicago and Washington, D.C., and ultimately, regions, states and continents.