Carl Trumbull Hayden (October 2,1877-January 25,1972) was the first United States Senator to serve seven terms, and holds the record for longest service in the United States Congress - he served continuously from February 19, 1912 to January 3, 1969.

He was born in Maricopa County, Arizona almost 35 years before Arizona became a state. The town where he was born was then named for his family, as Hayden's Ferry, but not long afterward received its current name of Tempe. After serving as county treasurer and sheriff he became Arizona's first member of the United States House of Representatives when statehood was granted in 1912.

He served in the House uninterruptedly until joining the United States Senate in March 1927 after winning the election to the first of seven terms in 1926. A constitutional amendment changing the starting date of terms meant that his retirement took effect in January 1969. A Democrat, Hayden became Chairman of the Appropriations Committee and President pro tempore of the United States Senate in 1957, ascending to both offices by seniority, as his party then held the majority in the Senate and continued to do so for the rest of his time in office.

It was more or less an open secret that Hayden was descending into senility during his last two terms in office. Nevertheless, he generally retained the support of the Arizona establishment, who wanted to counter neighboring California's numerical advantage in the House - his seniority was a valuable asset in securing federally controlled irrigation projects desired by both states. One anecdote of this time is of Hayden walking into a telephone booth in the Senate cloakroom, thinking it was an elevator, and saying, "Up, please." However, much like former German President Paul von Hindenburg, in a similar condition during the twilight of his life, Hayden was typically attended by an aide who could keep an eye on him.

His record for length of service in the Senate has now been surpassed by Strom Thurmond, Robert C. Byrd, and Edward M. Kennedy, but his record for combined length of service in both houses of fifty-six years, ten months and fifteen days has yet to be equalled.

He died in his native county and his ashes were interred in a family plot in Tempe.