1. the Atlantic Ocean
   the Pacific Ocean
2. the Salton Sea
   the Southern Ocean

The Atlantic Ocean, which covers about 20 percent of Earth's surface, borders the U.S. East Coast.

1. the Rocky Mountain Range
   the Oregon Coast Range
2. the Appalachian Mountain Range
   the Alaska Range

Although a small part of the Appalachian Mountain Range falls in southeastern Canada, most of the 1,500-mile chain falls in the United States. The Appalachian Trail, a 2,175-mile hiking trail, runs from Mount Katahdin, in Maine, south to Springer Mountain, in Georgia.

1. California
   Florida
2. Illinois
   Maine

Utah, Nevada and Arizona between the Sierra Nevada and Rocky Mountains is where these winds, known as "red winds," form. Warm, dry air blows down the mountains and into southern California.

1. Estonia
   Liechtenstein
2. Russia
   Slovakia

The U.S.landmass, at 3.7 million square miles, is about half the size of Russia, which measure 6.6 million square miles.

1. the Everglades
   the Great Basin
2. the Gulf of Mexico
   the Hudson Bay

The Everglades, a watershed that accounts for about one-third of southern Florida, extends south from Lake Okeechobee into Florida Bay.

1. Colorado River
   Hudson River
2. Mississippi River
   Missouri River

The Missouri River, the longest in North America, flows east and south for 2,341 miles. And, both the Colorado River, at 1,450-miles-long, and the 2,320-mile Mississippi River are two of the three major rivers in the U.S. But the Hudson River, which flows through New York, is just 315 miles long.

1. Florida
   Maine
2. Massachusetts
   North Carolina

The easternmost point in the 48 states is West Quoddy Head, in Quoddy Head State Park, in Lubec, Maine. Its lighthouse, West Quoddy Head Light Station, was added to the National Register of Historic Places in 1980.

1. north, toward Canada
   south, toward the Gulf of Mexico
2. east, toward Ohio
   west, toward Montant

The river originates in northern Minnesota and runs southward toward the Mississippi River Delta, at the Gulf of Mexico.

1. the White Mountains
   the Rocky Mountains
2. the Pacific Coast Ranges
   the Alps

Beginning in northwestern Canada, the Western Continental Divide is an invisible line that runs south along the Rocky Mountains through the U.S., and then continues south, running along the Sierra Madre Occidental Mountains in Mexico.

1. 1
   2
2. 5
   50

There are five geographic regions in the U.S.: the northeast, southwest, west, southeast and midwest.

1. New Mexico
   Oklahoma
2. Texas
   none of these

The Grand Canyon, which is deep enough to fit 19 stacked Statues of Liberty, fits entirely in Arizona.

1. Delaware
   Hawaii
2. Maryland
   Rhode Island

Wyoming may be the smallest state when it comes to population, but when you're talking land mass, Wyoming is the actually the 10th-biggest state. But, at just 48 miles long and 37 miles wide, Rhode Island is the smallest state (with more than 384 miles of coastline).

1. Mount Whitney, in the Sierra Nevada Mountains
   Grand Teton, in the Teton Range
2. Cloud Peak, in the Bighorn Mountains
   Bald Mountain, in the Rocky Mountains

While the top 10 highest summits in the U.S. are in Alaska, the tallest in the contiguous states, at 14,505 feet, is Mount Whitney, on the eastern side of California's Sierra Nevada Mountains.

1. Alaska
   Colorado
2. Oregon
   Utah

The Rainbow Bridge, found on the Colorado Plateau, is 290 feet above the ground and 275-feet across. More than 85,000 people from around the world visit Utah every year to see it.

1. yes
   no
2. only with special equipment

Technically, yes, this is true. At their closest point, the U.S. island of Little Diomede is just two and a half miles from the Russian island of Big Diomede. There are other places for viewing Russia from Alaska, too, if you go to high ground.

1. city
   state
2. it's both a city and a state
   actually, it's a federal district

Since it was founded in 1790, Washington, D.C., has been neither a city nor a state. It's a federal district (the D.C. stands for "District of Columbia") -- and the capital of the United States.

1. Colorado
   Nebraska
2. New Mexico
   all of these are in the Great Plains

States considered part of the Great Plains, a high plateau region east of the Rockies and west of the Mississippi River, include: Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming.

1. Denali
   Fairweather Mountain
2. Mount Hubbard
   Mount Silverthrone

At 20,310 feet, Denali (formerly Mount McKinley), in the Alaska Range, is the highest elevation in Alaska and in the United States. Conversely, the lowest elevation in the state is sea level.

1. Connecticut
   New Hampshire
2. New York
   Rhode Island

The six states that make up New England include: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont. New York, which is a state in the Northeast, is not part of New England.

1. the Chattahoochee River
   the Rio Grande
2. the Roe River
   the Snake River

The Roe River, which flows between Giant Springs and the Missouri River near Great Falls, Montana, is world's shortest river (as recognized by the Guinness Book of World Records). It's, at most, just 200 feet long, but has measures as little as 58 feet in length.

1. Chihuahuan Desert
   Mohave Desert
2. Patagonian Desert
   Sonoran Desert

The Chihuahuan Desert, Mohave Desert and Sonoran Desert, as well as the Great Basin Desert, are all part of the American West and Southwest. The Patagonian Desert, however, is a 200,000-square mile area in, primarily, Argentina.

1. California's Mount Shasta volcano
   Hawaii's Kilauea volcano
2. Oregon's Crater Lake volcano
   Washington's Mount St. Helens volcano

Active since 1983, Hawaii's Kilauea volcano is considered the most dangerous in the U.S.

1. the Columbia River
   the Mississippi River
2. the Saint Lawrence River
   the Yukon River

After a series of three major 8.0-magnitude earthquakes struck near Missouri in 1812, a phenomenon called a "fluvial tsunami" caused the Mississippi River to flow backward for several hours.

1. Badwater Basin in Death Valley, California
   New Orleans, Louisiana
2. Mount Greylock, Massachusetts
   Lake Champlain, Vermont

Unlike geographical phenomenons like the Grand Canyon, Death Valley isn't the result of river erosion. How, then, did it sink to 282 feet below sea level? Badwater Basin in Death Valley National Park is the result of topographical movements in the Earth's crusts.

1. Lake Erie
   Lake Heron
   Lake Michigan
2. Lake Ontario
   Lake Superior

Of the Great Lakes, Lake Superior -- at 31,820 square miles -- is the largest of the five and the largest freshwater lake in the world.

1. Idaho
   Kentucky
2. Tennessee
   West Virginia

The Mammoth-Flint caves, at 300 miles long, are the largest underground caves in Kentucky, and the world.

1. Florida
   Georgia
2. Pennsylvania
   all of these states

The ECD begins at the Twin Tiers of New York and runs south through Pennsylvania, West Virginia, Virginia, both North and South Carolina, into Georgia (and right through the city of Atlanta), all the way to the most southern tip of Florida.

1. Maryland and Pennsylvania
   Kentucky and Tennessee
2. New Mexico and Mexico
   North Carolina and South Carolina

The Mason-Dixon Line is a figurative line running along the boundary between Maryland and Pennsylvania. Over the 250 years since it was surveyed, it eventually became a symbol of the splintering between the Northern free states and the Southern slave states during the Civil War.

1. Canada
   Greenland
2. Mexico
   Russia

Some of the 14 larger volcanic islands and 55 smaller ones that make up the Aleutian Island chain belong to the United States (they're part of the state of Alaska), and some belong to Russia.

1. Arctic Coast
   Atlantic Coast
2. Gulf Coast
   Pacific Coast

At 7,623 miles, the Pacific Coast, the longest U.S. seacoast, is more than 3 1/2 times longer than its opposite coast, the Atlantic.

1. Boulder City
   Henderson
2. Las Vegas
   Reno

Reno, the "Biggest Little City in the World," is 300 miles from the Pacific Ocean, and a little more than 80 miles farther west than Los Angeles, California.

1. an estuary
   an islet
2. a low marsh
   a tidal marsh

The Chesapeake Bay is the largest estuary in North America. It's part of Maryland and Virginia, with more than 150 major rivers and streams flow into it.

1. Minnesota River Valley
   Monument Valley
2. Red River Valley
   Silicon Valley

You'll find that 3.8 billion-year-old rock in the Minnesota River Valley, in Minnesota.

1. near Belle Fourche, South Dakota
   in Lebanon, Kansas
2. near Rugby, North Dakota
   none of these

You'll find the geographic center of the 50 states is near Belle Fourche in Butte County, South Dakota. In the 48 states sharing a boundary, the center is near Lebanon in Smith County, Kansas. And the geographical center of North America? That's near Rugby, North Dakota.

1. Alaska
   Canada
2. Hawaii
   Mexico

Canada is the United States' northern neighbor. The two countries share a 5,524 mile border. To the south, the U.S. shares a 1,989-mile border with Mexico.