This video explains how to overlay histogram plots in R for 3 common cases: overlaying a histogram with a normal curve, overlaying a histogram with a density curve, and overlaying a histogram with a second data series plotted on a secondary axis.
Note: Towards the end of the video (maybe minute 14 or so), I make a language error when talking about the “padj” parameter in the mtext function…the setting doesn’t “left truncated” the label, I meant “right align”, “left align”, etc.
Download:
Histogram overlay in R code and sample data file




