The Platte River Valley served as a pathway for several hundred thousand pioneers who made the long trek west during the mid-19th century in search of a new life.

The Great Platte River Road, along the valley’s 310-mile river, guided fortune-seekers as they traveled to the California gold fields, Mormons in search of the promised land and the Pony Express during its abbreviated, 18-month life.

Though no longer a major throughway, a 70-mile stretch of the Platte River Valley in Nebraska continues as a waypoint for some of the earth’s most beautiful creatures.

Twice each year, hundreds of thousands of sandhill cranes choose the Platte River Valley as a resting place and staging area during migrations between the southern United States and Mexico, and the northern U.S., Canada, Alaska, and Siberia. During their migrations, the cranes fly 300 to 500 miles per day, depending upon the wind, during pilgrimages that can range up to 10,000 miles.

The central flyway of the sandhill cranes is hourglass-shaped, with a 70-mile stretch of the Platte River Valley as its chokepoint. A smaller eastern flyway connects Florida with Michigan and northern Indiana. Smaller ones exist to the west, as well.

But it is central Nebraska that draws the vast majority of sandhill cranes — and human visitors who come to witness their flight.

We visited during the spring migration that generally begins in late February. Their population peaks in mid- to late-March (which is also the peak for human visitors, so reservations for lodging and tours should be made well in advance.)

In our other travels we’ve seen mountain goats in Glacier National Park, wolves in Yellowstone and alligators in the Everglades. We’ve watched a cougar run beside the lodge registration building in Big Bend National Park, and we’ve gone whale watching in Glacier Bay, Alaska. Only the latter compares to the spectacle of Nebraska’s sandhill crane migration.

About a half-million cranes stop along the Platte River Valley twice each year to rest, feed and, depending on their status, find a mate, before completing the journey.

In the spring, they fly north to nesting grounds. In the fall, they journey south to escape harsh winter weather.

It is estimated that more than 90 percent of the mid-continent population of cranes channel their migration through Nebraska.

Although several species of sandhill cranes populate North America, all the birds are relatively large in size and have long, thin necks and legs. Feathers tend toward various shades of gray, often brushed with reddish streaks that result from preening by the cranes using brown or red mud.

Foreheads are decked with bright, red skin that makes them easy to identify. The birds range from 3- to 4-feet in height, with giant wingspans that power them over long distances. Large wings and sleek bodies accentuate the beauty of the cranes in flight or as they glide in for a landing.

Unlike many humans, sandhill cranes mate for life, which can span 20 years and longer. Unattached adults seek a mate during the spring migration. This search often includes one of most enjoyable sights for bird watchers – the dance.

Sandhill cranes flap their wings, bow, pump their heads, and jump up and down during courting dances. Sandbars in the Platte often become a bird version of the disco-era Studio 54.

During spring migrations, cranes stop in this narrow section of the valley and spend two to four weeks resting and feeding in the surrounding fields. They mostly eat corn that remains from the fall harvest.

From 80,000 to 100,000 cranes are in the valley at any one time from mid-February through early April.

Sandhill cranes don’t fish but consume insects, berries, worms and mice. Corn is an easy-to-find meal and their major food source in Nebraska. This is the Cornhusker State, after all. And the cranes eat well when they visit, adding 20 percent to their body weight during the Nebraska stopover.

Each morning near dawn, cranes commence the search for food. They generally don’t have far to fly because the river is surrounded by cornfields.

The best places to see the cranes here are near the towns of Kearney and Grand Island, both of which are along Interstate 80 in south-central Nebraska.

The Iain Nicholson Audubon Center at Rowe Sanctuary, about 25 minutes southeast of Kearney, offers several group viewing blinds alongside the Platte River. Volunteers guide visitors to the blinds during darkness for morning viewings and before sunset for evening viewings.

Good views are also available at the Fort Kearny Recreation Area Hike-Bike Trail Bridge.

Further east a short distance off Interstate 80, at Exit 305, the Crane Trust offers morning and evening guided tours to its private blinds and to a private footbridge. The blinds are enclosed and have large plastic windows for viewing while the bridge tour allows 360-degree viewing.

Grand Island claims more cranes than Kearney, which bills itself as the “sandhill crane capital of the world.” But both are excellent places from which to view the migration.

Once cranes finish feeding, their departures are sometimes gradual, with small- or intermediate-size groups leaving together. Sometimes they take off in mass.

Regardless, it is quite a sight when hundreds or thousands of cranes take flight together.

At dusk, the sight of thousands of returning cranes is simply breathtaking. Approaching in V-shaped formations or long wavering columns, cranes descend like supersonic aircraft, landing with full flaps down.

Perhaps most memorable is the trilling and purring from thousands of cranes prior to lift-off. Upon leaving the blind where we watched the cranes, one person in our group said, “We will carry that sound with us forever.”

David and Kay Scott are authors of “Complete Guide to the National Park Lodges” (Globe Pequot). Visit them at www.valdosta.edu/~dlscott/Scott.