In case anyone actually wants to know the answer: it’s the plot of Cars. The difference is literally the plot of Cars.
Highways are usually two-to-four (at the widest) lane roads that meander the US landscape. Think Route 66, dinosaur statues, mom-and-pop diners, southern gothic. There are state-level and national-level highways. Some run for a 100 miles, some, like US HWY-17, run most of the East Coast:
That red line is US HWY 17. If you follow it, you will go through tiny towns. You may hit stoplights. I kid you not, you will see spinning cows on poles. Businesses exist along highways that you are encouraged to pull over and visit. They were designed to let you see America.
Yeah.
Now, interstates were made in the 50s and were made to get people from Point A to Point B. These suckers range from four lanes to eight lanes around big cities. They cut through everything. If you want to get to a business, you have to take an exit ramp and detour. They are great for getting places fast. You can still have weird experiences on them, but usually at night, when your eyes start playing tricks on you. Or there are deer.
I-95 is a massive corridor that runs from the Florida Keys to the Canadian Border. You can see the difference just looking at the maps.
As far as writing goes:
If you want quirky character development inside the car, you’re looking for an interstate. The majority of Americans take interstates to go on road trips.
If you want mysterious and/or supernatural hijinks, you’re looking for a highway. They are weird, weird places, and they’re surprisingly easy to wind up on if you leave the interstate.
(Even in America, no one’s really sure what a freeway is. Just ignore it.)
Freeways exist in big cities where cars are more prominent than public transport, such as LA or Atlanta. You’ve year of liminal spaces? Freeways during rush hour are a physical manifestation of hell.
Awesome! Now what the hell is a turnpike?
If you find out, let me know. Maybe ask someone from New Jersey.
A turnpike is a highway with a toll. Turnpikes are special highways where you drive really fast and it’s usually linking big cities with each other and you keep going until you hit a toll booth.
They’re called “turnpikes” because in the olden days, there were pikes or barriers up and you had to pay the toll for them to be raised or turned to let you in.
For everyone who didn’t want to know, expressways are a form of highway that connect both suburban areas and major interstates to a city They often have both an alphanumerical name and a colloquial name In Philly we have the Schuylkill Expressway (I-76)
Would like to add that highways and mainly interstates were made specifically so THE MILITARY could get from Point A to Point B. This combined with a post-WWII boost in the economy and car industry gave Americans the ability to tour the country on their own for the first time ever. A whole chunk of American culture was created by just expanding the road system.
Think about road systems and other systems of travel when worldbuilding!
All this being said, most East Coast US people will refer to all of these things interchangeably as “highways”/”the highway.”
This may just be US East Coast metro areas, but I always thought a freeway was a raised expressway. As in, a stretch of limited-access road that lets you zip over a bunch of local streets (or some tricky geographic feature) without having to build the road on the ground. It looks like an overpass along its whole length.
I now realize that’s because there aren’t an awful lot of ways to build a controlled-access highway through dense urban areas. But other East Coast city people might have similar associations, because the ones that are actually called freeways tend to be closer in, and thus elevated. They’re usually short-ish and have specific names (“North-South Freeway,” “Whitehurst Freeway”). The only generic thing I’d ever be tempted to refer to as a “freeway,” not-otherwise-specified, is the raised structure itself.
(Parkway: slightly smaller and more scenic than the interstate and following a similar path, with no trucks allowed. Turnpike: limited-access highway with tolls (usually calculated by distance travelled) and very spaced-out/infrequent exits, meant for covering long distances with a minimum of local traffic. Thruway: like a turnpike, but may or may not have tolls. Beltway: a loop of interstate that encircles a metro area, whose number is generally one extra digit tacked onto whatever the major interstate passing through town is: for example, in the I-95 corridor, Baltimore’s is I-695 and DC’s is I-495.)
Other random us highway facts. Odd numbers are north/south (I-95) and even are east/west (I-90)
If it’s an even 3 digit number, like say I- 495, it’s usually a loop around a city. If it’s odd though, it’s a spur (like 195) with one end on the interstate, the other end leading to a town or highway or something else.
