Over the past 110 years, 504 boys and 26 842 girls have been named Lou. The name Lou ranks 3355th in the United States among the most common names for boys. For the first time more than ten times newborns were named Lou in 1915. The peak of popularity of the name Lou came in the 1920s and 1960s. You can see absolute numbers and relative numbers on the chart. Indicators per 100K more accurately assess the popularity of the name.