Over the past 110 years, 175 444 girls and 101 boys have been named Jo. The name Jo ranks 206th in the United States among the most common names for girls. For the first time more than ten times newborns were named Jo in 1910. The peak of popularity of the name Jo came in the 1940s and 1950s. You can see absolute numbers and relative numbers on the chart. Indicators per 100K more accurately assess the popularity of the name.