This chart uses a dataset I found on a wikipedia page attempting to compare the ridership and revenues on one Amtrak route, the Pennsylvanian.

The chart on wikipedia is a horrible visualization; it's a bar chart with two series, each mapped to a different axis with a different scale. Generally, bar charts with series should use the same scale, as they are designed to facilitate comparison of items in the same group.

You can look at the Wikipedia chart yourself at this link. (Wikipedia pages can change over time, but this link was active as of the time of the creation of this page, October 2020.)

I decided to see if I could improve this visualization. I experimented with a couple of ideas, including a scatter comparing the two data relationship between the two items on the X and Y axes, but that failed to include the trend over time, which I believe is important to this story, too. Ultimately, I ended up keeping the dual axes, but changed one of the series to be points and lines instead of bars, so that the chart would not look like the two series should be compared in the same year. I also changed the color scheme to some softer tones, using colors I found in the Sunlight Foundation Style Guide.