For centuries, European explorers sought an easy trade route to Asia--one that connected the Atlantic and Pacific Oceans. Many believed that a "Northwest Passage" existed along the northern coast of North America. But a maze of islands and frozen polar waters hindered the ultimate discovery and navigation of this longed-for route until early in the 1900s.

Under the command of Norwegian explorer Roald Amundsen, the Gjoa was the first ship to sail the entire Northwest Passage. Amundsen and six crew members left Kristiania (present-day Oslo), Norway, in June 1903 and arrived at Nome, Alaska, in September 1906.

In 1909, two Americans claimed to have reached the North Pole: Dr. Frederick Cook and Robert Peary. But who was first? Cook asserted he arrived at the Pole in April 1908; Peary declared he made it to the Pole in April 1909. Both explorers had their supporters and detractors.

Poor documentation of Frederick Cook's and Robert Peary's expeditions only heightened the ensuing debate. Serious questions arose about the veracity of Cook's report. Backers of Peary praised his claim, though it was also suspect. Both explorers published accounts of their treks to the Pole. The prize went to Peary.

With one pole conquered, explorers began the race for the other prize: the South Pole. Two contenders set off in 1911. Norwegian Roald Amundsen was first to reach the pole on December 14, 1911. British explorer Robert Falcon Scott arrived more than a month later, in January 1912. Tragically, Scott and his party perished during their return, victims of the freezing weather of the Antarctic summer.

Many citizens, businesses, and civic and private organizations from Detroit, Michigan, supported George Wilkins' expeditions. Edsel Ford made such a generous donation that Wilkins sent this handwritten letter personally thanking Ford for his contribution.

Edsel Ford supported other polar explorers during the 1920s. When Richard Byrd proposed a flight over the North Pole with pilot Floyd Bennett, he turned to Ford for financial support. Not only did Ford provide considerable aid himself, but he also encouraged other business leaders to contribute as well. Following Byrd's flight, he wrote to Edsel Ford: "I owe more to you than all the rest put together."

Kings Bay, Spitsbergen, Norway, became the starting point for two historic polar flights in 1926. Richard Byrd and Floyd Bennett planned to fly to the North Pole and back, while Roald Amundsen and American explorer and adventurer Lincoln Ellsworth intended to fly over the Pole and cross the Arctic Ocean in an airship. The two expeditions arrived in April and crowded the small coastal community.

Polar explorers Roald Amundsen and Lincoln Ellsworth secured the Italian semi-rigid airship N1--rechristened Norge after Amundsen's native Norway--and hired its designer Umberto Nobile to pilot it for the flight across the Arctic Ocean. Amundsen and Ellsworth landed in Kings Bay, Norway, in mid-April 1926 to prepare the airship's hangar. The Norge would arrive in early May.

On May 9, 1926, Richard Byrd and pilot Floyd Bennett flew toward the North Pole in a Fokker F.VII Tri-Motor airplane. Edsel Ford provided considerable financial support to the expedition, and Byrd named his airplane Josephine Ford to honor Mr. Ford's young daughter. Though Byrd is generally credited with reaching the pole, controversy remains about whether he could have made the 1,350-mile journey in the elapsed time.

A few days after Richard Byrd's flight, Roald Amundsen, Lincoln Ellsworth, Umberto Nobile, and a crew of 13 began their journey. On May 12, 1926, the airship Norge flew over the North Pole--the first confirmed visit to the pole. The Norge continued south. After staying aloft for more than 70 hours and traveling nearly 3,200 miles, the airship landed in Alaska. The expedition members had become the first to fly across the Arctic.

Umberto Nobile returned to Kings Bay, Norway, in 1928, leading his own expedition and commanding the airship Italia. Nobile planned to conduct scientific flights over the Arctic. He flew successfully over several Russian archipelagos during Italia's second flight and headed back to the North Pole on its third.

Umberto Nobile reached the North Pole for a second time in May 1928. Unfortunately, Italia crashed on the Arctic ice 180 miles northeast of Kings Bay, Norway, during its return. An international rescue mission found the survivors weeks later. Nobile was injured but survived; seven members of the expedition died. Tragically, Roald Amundsen also perished during one of the many missions to look for the lost airship crew.

After his flight to the North Pole, Richard Byrd led a scientific expedition to study Antarctica and to fly over the South Pole. The expedition embarked in late 1928, and in 1929 Byrd established the base Little America on the Ross Ice Shelf. From here, he would make his historic flight.

Richard Byrd chose a rugged and dependable Ford Tri-Motor for his attempt to fly to the pole. He named the airplane Floyd Bennett after the pilot who accompanied him on his North Pole flight. (Bennett passed away in April 1928 before the Antarctic expedition got underway.) On November 28-29, 1929, Byrd and a crew of three became the first to fly over the South Pole.

Published accounts of polar expeditions provided the public with information about the newest discoveries. Books also gave explorers the needed publicity to continue funding future ventures. Richard Byrd detailed the accounts of his first Antarctic expedition in this book, championing his scientific research and leadership and leaving no doubts about the validity of his South Pole flight.

After his historic flight across the Arctic Ocean by airplane in 1928, George Hubert Wilkins continued his polar explorations. In the late 1920s, Wilkins led expeditions to map the Antarctic coast. In 1931 he bought a submarine and ventured under the Arctic pack ice. Wilkins also supported Lincoln Ellsworth's expeditions to fly across Antarctica during the 1930s.

In 1900, the Northwest Passage was unnavigated, the vast Antarctic continent largely unstudied, and the Earth's Poles unconquered. But within the next forty years, intrepid polar pioneers--backed by wealthy patrons, governments, and scientific and civic organizations--opened these frozen worlds to continued discoveries by today's scientists, explorers, and adventurers.