He offered dentistry services to miners and invested in real estate and mining stocks, becoming one of San Francisco's first millionaires.

[24] Along with this, many of the fountains were installed incorrectly leading to a hot, high velocity water jet rather than the cool slow stream promised by Cogswell.

[26] Although the D.C. statue survived mostly unscathed, the San Francisco one was torn down by "a lynch party of self-professed art lovers" including Gelett Burgess (who was subsequently fired from his job at University of California at Berkeley)[27] and one in Rockville, Connecticut, was thrown into Shenipsic Lake.

[28] In Dubuque, Iowa, a statue of Cogswell that sat in Washington Park was pulled down by a group of vandals in 1900 and buried under the ground of a planned sidewalk.

[30] The diaries of Cogswell and his wife Caroline cover 37 years (1860–1897) and are an unusually long and consistent record of busy personal and financial life in the western United States.