Casimir has been given to about 5,248 people in the United States since 1880. It was most common in 1919, which makes it a Edwardian name.
Its best year was 1919, when 220 babies were given the name, ranking 395th. The typical living American called Casimir is about 47 years old today. It is relatively most common in Colorado, where it accounts for 0.01% of births.
Source: US Social Security Administration, national and state name files, 2025 release, and the Office for National Statistics for England and Wales. Etymology researched and written by our editors. Living-population and median-age figures are our own estimates, described in the methodology.