The online National Atlas of the United States of America provides a wealth of mapped environmental data you can incorporate into your coverage. You can dial up just one layer of data, or add layer after layer to create your own concoction of interlinked factors. The zoom function allows you to narrow or enlarge your geographic coverage as you see fit.

The available maps cover a huge range of topics, such as:

• Average seasonal sea surface temperatures
• Tornado occurrence from 1950-2008
• Locations of Superfund and Toxics Release Inventory sites
• Percentage of farms with sales greater than $10,000
• Forest cover types
• Arsenic in groundwater
• Red-backed salamander distribution

There are scores of other layers under topics such as agriculture, people, boundaries, climate, history, geology, biology, and environment. Take some time to explore the site to see if what you need is available, or can be created.

• National Atlas. [2]