In 1835, Leffler moved to the area that is now Burlington,
Des Moines County, Iowa—then part of the
Michigan Territory. At the time, Iowa and the other regions of the Michigan Territory west of the
Mississippi River were broadly divided between Des Moines County in the south and Dubuque County in the north. Leffler was admitted to the Des Moines County bar on April 15, 1835, and practiced law. While under Michigan's regional governance, he was named as the chief justice of the first judicial tribunal of Des Moines County on April 11, 1836. After the creation of
Wisconsin Territory on April 20, 1836, he served in the
first legislature of the new Territory from 1836 through 1838, and served as Speaker of the House during the 2nd session of the Assembly, in the winter of 1837–38. After
Iowa Territory was created from areas of Wisconsin Territory west of the Mississippi River—previously referred to as the
Iowa District—in 1838, he served as a member of the Iowa Territory house of representatives in 1841. President John Tyler appointed Leffler as
United States marshal for the district of Iowa on December 18, 1843. He served until removed by President James K. Polk on December 29, 1845, when he resumed the practice of law in Burlington. He declined the appointment of the register of the land office at Stillwater (in what was then
Minnesota Territory) in 1849. He was appointed by President
Millard Fillmore as receiver of public sums of money for the Chariton land district of Iowa on August 30, 1852, and served on that position until removed by President
Franklin Pierce on March 29, 1853. He died in
Chariton, Iowa, on March 8, 1866, at age 77. He was interred in
Aspen Grove Cemetery, in Burlington. ==References==