Lucien Lester Ainsworth was a one-term Democratic U.S. Representative

United States House of Representatives

The United States House of Representatives is one of the two Houses of the United States Congress, the bicameral legislature which also includes the Senate.The composition and powers of the House are established in Article One of the Constitution...

 from Iowa's 3rd congressional district

Iowa's 3rd congressional district

Iowa's 3rd congressional district is a congressional district in the U.S. state of Iowa that currently covers an area from Des Moines to the western outskirts of the Cedar Falls-Waterloo Metropolitan Area to the western outskirts of the Cedar Rapids area and to Lucas and Monroe counties .The...

 in northeastern Iowa

Iowa

Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...

.

Born in New Woodstock, New York, Ainsworth attended the public schools, and the Oneida Conference Seminary, Cazenovia, New York

Cazenovia, New York

Cazenovia is a town in Madison County, New York, United States. The population was 6,481 at the 2000 census. The town is named after Theophilus Cazenove, an agent of the Holland Land Company.The Town of Cazenovia has a village also named Cazenovia...

.
After studying law, he was admitted to the bar

Admission to the bar in the United States

In the United States, admission to the bar is the granting of permission by a particular court system to a lawyer to practice law in that system. Each U.S. state and similar jurisdiction has its own court system and sets its own rules for bar admission , which can lead to different admission...

 in Madison County, New York

Madison County, New York

Madison County is a county located in the U.S. state of New York. As of the 2010 census, the population was 73,442. It is named after James Madison, fourth President of the United States of America...

, in 1854.
He moved to Belvidere, Illinois

Belvidere, Illinois

Belvidere is a city in Boone County, Illinois, United States. The population was 25,585 as of the 2010 census. It is the county seat of Boone County. Belvidere is part of the Rockford, Illinois Metropolitan Statistical Area.-Geography:...

, and commenced practice the same year.

In 1855, he moved to Iowa and continued the practice of law in West Union

West Union, Iowa

West Union is a city in Fayette County, Iowa, United States. The population was 2,549 at the 2000 census. It is the county seat of Fayette County...

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He served as member of the Iowa Senate

Iowa Senate

The Iowa Senate is the upper house of the Iowa General Assembly. There are 50 members of the Senate, representing 50 single-member districts across the state with populations of approximately 59,500 per constituency. Each Senate district is composed of two House districts...

 from 1860 to 1862, representing Bremer and Fayette

Fayette County, Iowa

-2010 census:The 2010 census recorded a population of 20,880 in the county, with a population density of . There were 9,558 housing units, of which 8,634 were occupied.-2000 census:...

 Counties.
During the Civil War

American Civil War

The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

 entered the Union Army

Union Army

The Union Army was the land force that fought for the Union during the American Civil War. It was also known as the Federal Army, the U.S. Army, the Northern Army and the National Army...

 in 1862 as captain of Company C, 6th Regiment Iowa Volunteer Cavalry

6th Regiment Iowa Volunteer Cavalry

The 6th Regiment Iowa Volunteer Cavalry was an cavalry regiment that served in the Union Army during the American Civil War.-Service:The 6th Iowa Cavalry was mustered into Federal service at Davenport, Iowa for a three year enlistment between January 31 to March 5, 1863.The regiment was mustered...

, and served three years in areas of conflict with Native American

Indigenous peoples of the Americas

The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...

 tribes in the northern Great Plains

Great Plains

The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...

. He and his Company participated in the Battle of Whitestone Hill

Battle of Whitestone Hill

The Battle of White Stone Hill was a part of the operations against the Sioux in North Dakota in 1863. It took place between the dates of September 3–5, 1863. The principal United States commander was Brig. Gen. Alfred Sully, who faced Chief Inkpaduta of the Sioux. There was 822 total casualties;...

 in Dakota Territory

Dakota Territory

The Territory of Dakota was an organized incorporated territory of the United States that existed from March 2, 1861, until November 2, 1889, when the final extent of the reduced territory was split and admitted to the Union as the states of North and South Dakota.The Dakota Territory consisted of...

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After leaving the Army, he returned to West Union and resumed the practice of law.
He served as member of the Iowa House of Representatives

Iowa House of Representatives

The Iowa House of Representatives is the lower house of the Iowa General Assembly. There are 100 members of the House of Representatives, representing 100 single-member districts across the state with populations of approximately 29,750 for each constituency...

 from 1871 to 1873.

In 1874, Ainsworth ran as a Democrat

Democratic Party (United States)

The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...

 to represent Iowa's 3rd congressional district in the U.S. House. Becoming the first Iowa Democrat elected to Congress since 1854, he served in the Forty-fourth

44th United States Congress

The Forty-fourth United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met in Washington, D.C. from March 4, 1875 to March 4, 1877, during the seventh and...

Congress. He declined to accept a renomination in 1876. He served from March 4, 1875 to March 3, 1877.

He resumed the practice of law in West Union, and died there on April 19, 1902. He was interred in West Union Cemetery.