text: McCormick organized much of Carrie Chapman Catt's efforts to gain ratification for the Nineteenth Amendment. While working with Catt, she met other social activists, including Mary Dennett and Margaret Sanger. Katharine met Sanger in 1917, and later that year joined the Committee of 100, a group of women who practiced promoting the legalization of birth control.  During World War I, Katharine also worked as a chairwoman of the association's War Service Department. In addition, she was a member of the Women's Committee of the Council of National Defense. In 1920, after the Nineteenth Amendment  was ratified, McCormick became the vice president of the League of Women Voters.
  Throughout the 1920s, McCormick worked with Sanger on birth control issues. McCormick smuggled more than 1,000 diaphragms from Europe to New York City to Sanger's Clinical Research Bureau. She scheduled meetings with major European diaphragm manufacturers in cities such as Rome and Paris, and used her language skills and biology background to pose as a French or German scientist and place large orders for the devices. They were shipped to her family chateau, Prangins Castle, outside Geneva, where they were sewn into the linings of fashionable coats and other garments. She smuggled them past U.S. customs agents in New York, having successfully disguised them as the spoils of extravagant European shopping sprees for high-end fashions. She made these trips every summer from 1922 to 1925, retiring only after the 1925 Santa Barbara earthquake forced her to redirect her attention to rebuilding her husband's estate and devote her energy to helping direct his care.
  In 1927, McCormick hosted a reception of delegates attending the 1927 World Population Conference at her home in Geneva.  In that year McCormick also turned to the science of endocrinology to aid her husband, believing that a defective adrenal gland caused his schizophrenia.