This is in general a good article, but it needs a few things corrected before I will promote it formally to GA status:
There are no images in the article, except for the map. Is it possible to take a couple of pictures of notable places on the route?
The Reports of the State Roads Commission of Maryland are all deadlinks. Please review and replace the link if possible.
In the Future section, please clarify what a "streetscape improvement project" is.
In the junction list, the mileage jumps from 18.86 to 42.32 to 23.58. I guess this is because the road runs along I-68, and that is the Interstate's mileage, but could you consider putting either the US 220 or the I-68 mileage in parentheses under the other mileage. I think that would be significantly less confusing.
Two other things that will not impact GA status:
I made several copyedits; please review and make sure I did not distort or change the meaning of the sources.
For future articles, you might consider using
list-defined references, where the sources are listed at the end of the article in the references section instead of at first use in the wikitext. I have found using LDR makes articles significantly easier to copyedit.
Thank you for the review. To address your concerns:
I live far away from this highway, so I would not be able to take a few pictures of it in a timely manner. Besides, images are not required for a Good Article.
I fixed all of the deadlinks in the references. On your suggestion, I implemented list-defined references. I like how they work, so I will probably use them in the future in other articles.
A streetscape improvement involves stuff like putting in traffic calming features, building brick sidewalks, and other construction that makes a road more pleasant for pedestrians. Based on how inconsequential such an improvement is compared to a new bridge or a new alignment, I decided to remove that project from the Future section.