Fillmore County was formally organized in 1871 and was named in honor of Millard M. Fillmore. He studied law and in 1828 at age twenty-eight was elected to the New York State Assembly.
Later as a United States senator he was largely responsible for the passage of the Tariff of 1842, which protected American industry from foreign competition.
Despite an unsuccessful attempt to win the governorship of New York, he was elected vice-president of the United States in 1848. When the president, Zachary Taylor, died in office Fillmore led congress through the difficult passage of the Compromise of 1850, which postponed the Civil War for a few more years.
Fillmore also arranged the first land grants for railroad construction that would be so important to the settlement of the West. He chose not to seek re-election as president but did make an unsuccessful bid in 1856.