"Red Lion" - the name of a town? - I linked it because the reader who is not familiar with the topic won't know the specifics. - never mind, I linked it.
also I linked it to Red Lion, Delaware, because it helps to clarify that the road in Delaware then reaches Pennsylvania.
"With the construction of the DE 1 freeway in the 1990s, DE 7 was shifted to a portion of the freeway near the Christiana Mall and was extended south to an intersection with US 13 and DE 72 as a result of the relocation of US 13 onto a portion of the freeway." - long sentence that's hard to understand.
"In 1999, an interchange was built as DE 58 as a result of a northward extension of DE 1 along DE 7" - don't understand - an interchange is called DE 58?
I made a bunch of edits [1], with edit summaries explaining that full names should be used at first mention, especially in the lede but also in the body of the article as there are so many similar names that it's confusing; and that highway terms such as flyover and cloverleaf interchange should be linked.
Recommend more context be given when possible, especially in the body of the article: e.g. "the unincorporated community of Red Lion, Delaware - Christiana Mall, a super-regional shopping mall near Newark, Delaware, etc.
Recommend more attention given to prose: e.g. "Past this intersection, the route becomes Bear-Christiana Road and passes between suburban housing developments to the west and fields to the east." - using past/passes in the same sentence makes it harder for the reader to understand what is meant.