Young Ainsworth attended the public schools, and the Oneida Conference Seminary, in
Cazenovia, New York. "At intervals during his course at the seminary he taught school and was said to be a very popular teacher and educator." In 1854 at age 23, after studying law, he was
admitted to the bar in
Madison County, New York. That same year he moved to
Belvidere, Illinois, and began practicing law. Just a year later, in 1855, Ainsworth moved to Iowa and continued the practice of law in
West Union, where he would remain until his death in 1902. During the
Civil War in 1862, Ainsworth joined the
Union Army as captain of Company C,
6th Regiment Iowa Volunteer Cavalry, and served three years in areas of conflict with
Native American tribes in the northern
Great Plains. He and his company participated in the
Battle of Whitestone Hill in
Dakota Territory. After leaving the Army, he returned to West Union and resumed the practice of law. In 1885 Ainsworth continued his law practice. "We find the following local item telegraphed to the Cedar Rapids Republican from Fayette, March 6, 1885. The saloon of Simon Nefzger, at Lima, in this county, was raided night before last and a small quantity of whisky found yesterday morning. Nefzger and his clerk were both arrested for selling and the trial fixed for today. They came by their attorney, L. L. AINSWORTH, of West Union, proposing to quit the business totally and forever and pay all costs and expenses, including attorney for prosecution. Being satisfied that the proposition was made in good faith and would be adhered to, the prosecution did not appear. The costs were promptly paid and there is one less saloon in Iowa. It does prohibit." In 1890 Ainsworth was mentioned again. "A grave-stone law suit was in progress here last week between J. O. VanSyckel and some parties Strawberry Pointward, which lasted a couple of days. L.L. Ainsworth chopped up law for VanSyckel, and attorney Blair, of Manchester, assisted the defense. ==Political career==