This spectacular track has run continuously since 1882.

When ecosystems collide in the arid Southwest.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

The highest point in Washington state is a volcano covered in glaciers.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

One of the largest collections of wildlife art in the United States, built into the side of a cliff in rural Wyoming.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The air force base preserves its scars from the Japanese attack on Pearl Harbor.

This legendary urban waterfall creates a dazzling display of rainbows.

Hide from the tourist hordes in these relatively unknown, and unguarded lava caves.

Race through the maze, get your name on the sign.

Earth's tallest volcano is sacred to Native Hawaiians, and home to a dozen world-class observatories.

Originally a brothel during the Klondike Gold Rush, this bar once used dolls to denote when ladies were working.

One of two side-by-side totem pole parks dedicated to educating visitors on Tlingit history and culture.

Running under an entire mountain, the longest highway tunnel in North America is kept fresh using portal fans and jet fans.

A historic freight system that found the true gold rush is in tourism.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

A classic gold rush hotel can be expected to pick up some ghosts along the way, and the Golden North is no exception.

This WWII-era military installation once held an entire city within its walls - now, its walls are falling down.

A rare chance to get up close and personal with a 13-mile ribbon of ice near downtown Juneau.

The king of U.S. high points towers over every other peak on the continent.

The world-record holder for the longest bridge stretching continuously over water.

The second oldest continuously operating bar in Louisiana.

The obelisk meant to mark the founding father's grave at Monticello is actually on the University of Missouri campus.