[3][2]: 33 He practiced architecture for more than 50 years, designing schools and courthouses in Kansas and neighboring U.S. states.
A number of his works were listed on the U.S. National Register of Historic Places for their architecture.
The firm grew to a size of 46 architects, draftsmen, engineers and other specialists.
[2] He designed schools,[5] courthouses[2] and the Jayhawk Theater and linked hotel in Topeka in 1926.
Assisting Williamson was his chief designer Theodore R. Griest, and Linus Burr Smith from Kansas State College (now Kansas State University) to oversee the plans.