Securing a teaching position in Vacaville upon arrival in the West, in the fall of 1860 she accompanied the children of the Perkins family back across the Sierra mountains to their new home in Carson City. (Totten, p168) She saw a need for education there, she stayed and created a school and taught in Carson City for 25 years.

In 1861 Ms. Clapp and Mrs. Ellen Cutler begin to organize a private co-educational school, known as the Sierra Seminary. Its board of directors was composed of some of the most dynamic and illustrious men of the Comstock. They included Wm. Stewart, Territorial Gov. James Nye, Frank Perkins, and John W. North. The Territorial Legislature approved the school's Act of Incorporation and it was signed by the Governor Nov. 14, 1861.

By 1862, "Miss Clapp's school" was an established part of the community. It is believed that the Sierra Seminary provided the inspiration for Mark Twain's look at education and the examination process for some of his later works. Mark Twain visited the school in December 1862 and was known to be favorably impressed. (Totten, p. 169)

By July 1865, the Sierra Seminary opened a larger facility boarding 40 students. Ms. Clapp donated 10 acres of her own land to build the larger school. As the school grew there were changes in the administration, "...the Sierra Seminary into one of the foremost schools of the state. ...Some of their graduates became influential in several phases of Nevada's development, and many were accepted as students by universities in California and the East." (Totten, p.169)