I have a Pandas DataFrame containing the date that a stream gage started measuring flow and the date that the station was decommissioned. I want to generate a plot showing
While I do not know of any way to do this in MatplotLib, you may want to take a look at options with visualizing the data in the way you want by using D3, for example, with this library:
https://github.com/jiahuang/d3-timeline
If you must do it with Matplotlib, here is one way in which it has been done:
Matplotlib timelines