After Rehobeth, DE 1 heads Northeast towards Milford. There the first by-pass can be found, around Milford to US 113. This was the original end of DE 1. In the 1990's DE 1 was paired with US 113 to Dover, the State Capitol. DE 1 becomes an expressway, following the US 13 corridor.
Portions are still under construction and some of the road is toll.
The road reaches I-95 at the Christiana Mall. The most unusal aspect of DE 1 is that it assigns exit numbers in metric. I'm not sure exactly why, but I suspect that it's too make the state look bigger. At the northern terminus, I-95 is EXIT 165. When the route was first opened, the exits were numbered in English, therefore I-95 was EXIT 100.