He helped her father publish The Scourge of Aristocracy and Repository of Important Political Truth, a paper attacking U.S. president John Adams.

The Alien and Sedition Acts forced the family to flee the state, and in 1799, they settled at what is now Eddyville, Kentucky.

Matthew Lyon became a prosperous slave trader, which disappointed the anti-slavery Cadwell and his brother-in-law John Messinger.

Cadwell purchased 200 acres (81 ha) opposite Gaboret Island on the Mississippi River, about 9.5 miles (15.3 km) north of Cahokia, in what is now St. Clair County, Illinois.

In August 1813, he was named commissioner of the county court of common pleas, responsible for managing taxes.

In December 1820, he was named President pro tempore of the senate after Lieutenant Governor Pierre Menard requested a leave of absence.

He platted part of his claim as the town of Quincy, hoping to secure the location of the county seat.