Billboard Epic

If a series of billboards are related in that you're expected to read them one after another in order to get the entire message, they're a Billboard Epic.

There was a Saturday Night Live sketch where people drove down highways and could read an entire novel, from start to finish, on the billboards they drove past. The first one says, "Call me Ishmael" and the next billboard provides the following sentence.

Some car dealerships are almost this bad. You drive a few blocks, and the first one says, "You can always find..." and then a few blocks down you find a billboard saying "the best deals..." and then a mile away you see the punchline: "Stop in at Bob's Dodge in Leavenworth!" or whatever.

Live-Action TV
"Brought to you by the Petroleum industry."
 * As mentioned above, an early Saturday Night Live commercial sketch had entire novels were literally printed on billboards. They show all the people benefiting from this: a family taking a Sunday drive so their kids can read Swiss Family Robinson, a trucker claiming that once he finishes reading Sartre he can get his degree, an elderly couple talking about this being how they want to spend their retirement. And then the punchline:

Real Life

 * The most famous example, if not the Ur Example, were ads for Burma-Shave (The Other Wiki has an article here), which were arranged to form rhyming poems.
 * Back in The Eighties, the state of Virginia had signs done in the Burma Shave style in certain places along major highways (including a set at the airport entrance to the Dulles Toll Road warning regular traffic not to use the inside lanes). It probably helps that American Safety Razor (the company that owns Burma Shave) had one of their main plants in Virginia at the time.
 * In Illinois, perhaps elsewhere, people use Burma Shave style proto-billboard poems to advocate 2nd amendment rights, and the use of ethanol as a fuel additive.
 * On Twitter feeds / An odd regression / Ancient memes / Find new expression / Burma-Shave
 * On Interstate 95, South of the Border, an unremarkable Mexican-themed Tourist Trap on the North/South Carolina border. The ad campaign may be the closest thing to Real Life pop-up advertising. Starting somewhere in New Jersey on the north end and Georgia on the south, they brought hundreds of billboards up and down the east coast, bearing corny slogans and often telling the unfortunate driver exactly how far they are from the damn place. (ONLY 100 MORE MILES!) To this day, you can't make it though a state without seeing them in the tens. (They're at least useful for gauging how close you are to either North or South Carolina.)
 * Along I-10 from Texas west through Arizona are a series of billboards advertising "The Thing" in pretty much the same manner as South of the Border—and just about as annoying. The annoyance does help keep you awake through the empty stretches of highway in Texas and New Mexico.
 * On I-10 through Texas there are snarky billboards for Buc-Ees' rest stop outside of San Antonio. The first signs you see near the New Mexico and Louisiana state lines say, "Clean restrooms only 453 miles ahead! (Yeah, you can hold it)"
 * Similar to the above is Little America, on I-80 in Wyoming. This tourist trap has billboards for hundreds of miles. Once you get within 20 miles of the place, the billboards are incredibly thick... and of course tempting. Isn't it more fun to eat ice cream (or stop for a swim) than drive through Wyoming?
 * "Only 500 miles to Wall Drug, Wall, South Dakota": another tourist trap that runs billboards for hundreds of miles. They also offer free glasses of water, and back in the 1960s/1970s gave away hundreds of thousands of glasses of water a year, often to truck drivers.
 * South Dakota is the only state with unregulated billboards because the owner of Wall Drug was once the state's advertising regulator. Wall Drug will also make signs for visitors to post locally, which means there are Wall Drug signs all over the world. They even had advertisements in Paris and London's Underground for a while.
 * Anyone posted to Ft. Stewart, GA has had cause to drive along Highway 144. As a part of the new safety campaign, the US Army has posted roadside signs in just this manner along it. Some argue it does help keep drivers from falling asleep out of boredom.
 * There is a farmer's market in southern Ohio that puts up a bunch of signs like this, forming a sentence word by word. As kids, passing it on the way to a couple different festivals during the year, we thought that was pretty awesome.
 * Driving eastbound on Interstate 70 between Columbia (where the University of Missouri is located) and St. Louis, Missouri, there is a series of six billboards reading M I Z Z O U, playing on the call-and-response chant heard at sporting events. There's also smaller notes at the bottom about being the "#1 CHOICE OF MO H.S. SENIORS" and how to get tickets to games, because what's the point of billboards if you're not going to make money off of them?
 * Oddly enough, these billboards are only visible after leaving the town where the school is - why advertise something you've already passed?