Over the past 110 years, 101 boys and 175 444 girls have been named Jo. The name Jo ranks 5788th in the United States among the most common names for boys. For the first time more than ten times newborns were named Jo in 1920. The peak of popularity of the name Jo came in the 1920s and 1950s. You can see absolute numbers and relative numbers on the chart. Indicators per 100K more accurately assess the popularity of the name.