1	Interior Lowlands: US Corn Acreage
2	Interior Lowlands: US Soy Acreage
3	Interior Lowlands: Grain Belts The Interior Lowlands includes the Nashville Basin, the "Hill Country" of Texas, the Midwest, and vast stretches of flat to rolling land in Canada. A large part of this area is the "Breadbasket" of the United States - the Corn Belt. However, most of the corn grown here isn't for human consumption. Rather it is used as animal fodder. Fattening beef cattle and hogs is an important part of America's agricultural economy. Soy beans also mirror corn's growing area because both crops are usually grown in a corn-soy-fallow (i.e. year 1-2-3) pattern.
4	Interior Highlands: Ozarks & Ouachitas
5	Great Plains & Prairie Provinces The Great Plains covers nearly one-fifth of the continental United States. A vast stretch of prairie where few trees grow, these grasslands used to be tall grass prairie before it was noticed they would support dry field crops like wheat. It now serves as the western part of America's "Breadbasket." This is the Wheat Belt and the limited rainfall in the region is perfect for wheat cultivation. See what impact agricultural runoff (e.g. pesticides, herbicides, and fertilizers) can have on distant places by taking this link to the Mississippi Delta/Gulf of Mexico.
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7	Intermontane Basin & Plateau The Intermontane (literally "between the mountains") Basin and Plateau physical region is marked by extreme dryness, save the exotic streams that flow from the mountains. If you ever wondered why there are so many national parks in the area, you'll understand when you see that the lands are worthless in every way except to awe over (and maybe for some mining ventures). The western states are also glad to have the federal government maintain these public lands to save state operating funds. Without irrigation the area will not support agriculture. The dryness comes from the rain shadow effect of the Sierra Nevada Mountains and the Cascade Range. The mountains effectively block moisture that blows in from the Pacific Ocean. Thus, all the rainfall deposited on the windward (western) slopes leaves the leeward (eastern) slopes very dry. The Pacific Mountains and Valleys include Cascade Range of eastern Washington and Oregon, the Sierra Nevada of eastern California, and the Coastal Ranges that hug the coastline from southern California to the Gulf of Alaska. The highest mountain peaks of the continent are found here at Mt. Whitney (14,494' in California) and Mt. McKinley, or Denali (20,320' in Alaska). These mountains are especially important to the dry areas of California. Snowmelt from the mountains is channeled towards cities like Los Angeles because of continual water shortages. The Colorado River is also a big provider of water to southern California and the booming cities of Las Vegas and Phoenix.
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9	Pacific Mountains and Valleys
10	West Coast Tectonics Mount St. Helens was a volcanic peak in the Cascades of southwestern Washington; it erupted in 1980 killing 60 people in the area The San Andreas Fault is a strike-slip fault that is slowly partitioning California from mainland United States; earthquakes are frequent events here Both volcanoes and earthquakes here are caused by the clashing of the North America plate, the Pacific plate, and the Juan de Fuca plate
11	The Canadian Shield The Canadian Shield has experienced glacial scouring from the last ice age 11 to 13 thousand years ago. Notice all the glacial lakes of this area (e.g. Great Lakes, Lake Winnipeg, Great Bear Lake, Great Slave Lake, etc.) and the fjords of the island north. The islands of the Arctic realm (e.g. Baffin Island, Ellesmere Island, and Victoria Island) are all inscribed with former glacial troughs. Check the coastlines on a large-scale map of the region. You’ll see similar scouring along the coast of British Columbia and Alaska.
12	Arctic Coastal Plain