The recognition for being the longest serving justice in the history of U.S. Supreme Court goes to Justice William O. Douglas. After the retirement of Justice Louis Brandeis to Yakima, Washington. William O. Douglas was nominated by his friend President Franklin D. Roosevelt. At the age of 40, he was the second youngest Supreme Court justice in U.S. history, and he would serve for the next 36 years, 209 days from April 17, 1939 to November 12, 1975.

When Douglas retired from the Supreme Court, President Gerald Ford paid tribute by writing: "May I express on behalf of all our countrymen this nation's great gratitude for your more than thirty six years as a member of the Supreme Court. Your distinguished years of service are unequaled in all the history of the Court."

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