Samaritan asked me to tell them the difference between an expressway and a highway.

Expressway = Freeway: a highway with controlled access, usually with two or more lanes in each direction and divided by a median (middle divider).  The roads have slightly different names in different areas; in California they call them freeways.  Some are called interstate highways (see below).  You cannot enter an expressway at any location.  You have to enter at an on-ramp and exit at an exit.  That is why they call them "controlled access."

 

Interstate highway: a freeway or expressway that is part of the national US system of official "Interstate Highways" designated by the US congress.  All interstates are freeways / expressways.  Not all freeways or expressways are part of the official interstate highway system.

 

Highway: a general word for any primary road.  In includes freeways, interstates, expressways, and other US highways and even some state highways.

 

US highway: A primary road designated as a primary road by the US congress.  The "US Highway" system receives special funding from the US congress and is designated by the US congress as an official highway system.  Some US highways are freeways and expressways, but none are interstates.  The interstate system is a different system.  The numbering system of both US highways and interstates are the same nationwide, keeping the same number when they enter a different US state.  North/south US highways end in odd numbers (1, 3, 5, 7, 9); east/west highways end in even numbers.  For interstates, north/south interstate highways end in odd numbers (1, 3, 5, 7, 9); east/west interstate highways end in even numbers. 

 

State highways: US states also have internal highway systems called state roads or state highways.  Each state has its own system, so when you enter a new state on a state highway, the number and the numbering system usually changes.

 

County roads: Most roads not considered freeways, expressways, of national or state highways are usually called roads rather than highways.  But some are major roads and even a few have controlled access and are freeways.  Some are paved roads.  Some are dirt or gravel roads. 

 

City streets: Often cities have road systems that are not part of the above federal, state, or county systems.  Usually they are called streets, but some have names ending in street, road, lane, avenue, bouldevard, way, etc.  I live on Sixth Street, for example.   Most large cities have interstate highways, other expressways or freeways, state highways, county roads and highways, city streets and private roads.

 

Private roads: If no public road serves a private land owner's property, they may have private roads that are not open to the public.