A fun thought exercise. How many highways out there share both their number and common features (e.g. corridors, urban/rural split, scenery, widths, bridge types).
I'll start with one that made me think of this prompt: WA 6 and OR 6. Both are east-west highways crossing a small mountain range to connect US 101 on the Pacific Coast to I-5 (in the latter's case, via US 26). They are generally two-lane and don't pass through any major settlements of note except at a terminus. Both lack junctions except at/near their termini (OR 6 has a junction with OR 47 that is close to US 26; WA 6 has no intermediate junctions).