Putnam County, OH borders Allen near Ottawa metropolitan centre giving a 2020 estimated population standing at 34,877 making it the 28th most populous county located in Ohio overall. Its county seat is Ottawa with other cities include Fort Jennings & Columbus Grove-Ottawa itself equates out to Putnam's largestcity aside from noted country seat. This area had been created from Allen and Van Wert Counties back in 1820 when local citizens petitioned for new administrative boundaries - posthumously named after Congressman Israel Putnam magistracy era James Monroe .