Meant to add those things, thanks.
Alternate, Bypass, and Connector routes should have the same minimum type as their parents. There is only one "Scenic" route in the country
, so I would keep that Major too.
Business, City, and Loop routes should have the minimum type one type lower than their parents.
Spur routes are a bit difficult, since some states use "Spur" to designate connectors. When operating as a connector, it should be the same type as its parent for the sake of continuity. When it's just a spur into a city, though — basically a business route only connected at one end — it can be one type lower.
I will add "Minor Arterial". Meant to do so. Added notes on the "Other Freeways" states too.