quality:corruption, information:highlighting
Later years

Eastman was a presidential elector in 1900 and 1916. In 1915, Eastman founded the Bureau of Municipal Research in Rochester to gather information and make government policy recommendations. The agency was later renamed the Center for Governmental Research and continues to carry out that mission. In 1924, Eastman and the Bureau supported a referendum to change Rochester's government to a city manager system, which passed.

In 1920, Eastman established the Eastman Savings and Loan to provide financial services to Kodak employees. The institution was later rechartered as ESL Federal Credit Union.

In the 1920s, Eastman was involved in calendar reform and supported the 13-month per year International Fixed Calendar developed by Moses B. Cotsworth. On January 17, 1925, Eastman invited Cotsworth to his home; he had been introduced to Cotsworth's calendar by a mutual friend and was interested in the system. He secretly funded Cotsworth for a year and then openly supported him and the 13-month plan. Eastman took a major role in planning and financing the campaign for a new global calendar, and also headed the National Committee on Calendar Simplification, in the United States, which was created at the behest of the League of Nations. Eastman supported Cotsworth's campaign until his death.

Eastman wrote several articles to promote the 13-month system, including "Problems of Calendar Improvement" in Scientific American and "The Importance of Calendar Reform to the Business World" in Nation's Business. By 1928, the Kodak Company implemented the calendar in its business bookkeeping, and continued to use it until 1989. He was chairman of the National Committee on Calendar Simplification. Although a conference was held at the League of Nations in 1931, with his death and the looming tensions of World War II, this calendar was dropped from consideration.

In 1925 Eastman gave up his daily management of Kodak and officially retired as president. He remained associated with the company in a business executive capacity, as the chairman of the board, until his death.