The Future of Mason County Population Thanks to a recent conversation, I started wondering about the population of Mason County over the years since its founding. I knew we've had more people in the past; but, I was unsure of how many, and just what happened to them. Here are some of the interesting numbers I found at population.us that tell our story. 1860 - 630 1870 - 678 1880 - 2,655 1890 - 5,180 1900 - 5,573 1910 - 5,683 1920 - 4,824 1930 - 5,511 1940 - 5,378 1950 - 4,945 1 ...