The Putnam County Sentinel is the oldest continuously-operating business in Putnam County since operations started in 1855.

The newspaper began its life in Kalida, which was still the county seat at that time, as the Kalida Sentinel under the ownership of L. Wolfe. The newspaper remained in the village until after the Civil War, moving its operations to Ottawa in 1866. At that time the editor and publisher was M. G. Gillette and he changed the name to the current Putnam County Sentinel.

In 1867, Gillette sold the company to George D. Kinder who remained as editor and publisher of the newspaper until 1900 when he transferred the business to a stock company and incorporated as the Sentinel Publishing Company.

Throughout this time period in the county history, several newspapers started and ended their publishing lives, including the German publication, Der Democrat, The Ottawa Telegram, and the Putnam County Gazette. The Gazette stayed in business the longest, surviving through a series of owners until 1950 when the physical assets and the name were sold to the Sentinel Publishing Company.

Charles A. Schierloh served as the company manger of the Sentinel from 1900 until 1922 along with a line of five editors. The two positions were joined again in 1922 under the leadership when Edward J. Beckman was named the editor and manager until 1925. In January of that year, Edwin Sommers, then the superintendent of Ottawa Public Schools, became the publisher, editor and manager of the company. R.E. Laudick took over the editorial chair of the Sentinel in 1933 when Sommers - a very busy man - was also named the postmaster of Ottawa. Laudick added the managerial responsibilities in December of 1935 following the death of Sommers and remained an employee of the company for four decades.

Lillian Schierloh was also a long-time employee of the company. The daughter of Charles, she worked for the Sentinel for approximately 50 years, serving most of that time as a Linotype operator beginning with the installation of the first machine in 1919 and still working on the typesetting machines in the 1960s.

The Putnam Sentinel was purchased by the Hirt Publishing Company of Bellevue, Ohio, in 1984. The newspaper was later sold to Brown Publishing Company in 2005 and then DHI Media, Inc., of Delphos, in 2010.

Through all the changes of ownership and personnel, the Putnam County Sentinel has continued to serve the community by chronicling all the news, events, and people in the area.