The first drive-in opened on the Dallas - Fort Worth highway in October, 1921. The founder named it the Pig Stand due to it's barbecue menu but he did feel people in cars were lazy. This stand appealed to drivers so they could stay in their car, get a meal, and never leave it, especially if they were traveling.
When a car drove into the Pig Stand, a young man dressed in a white shirt with a black bow tie ran out to jump on the running board before it even stopped. The young men took the order for Texas Barbecue and coke, ran in to get it, brought it out on a tray that attached to the car window and were paid. These young men were called carhops and the idea was so popular the owners began franchising the Pig Stand with it's slogan of "America's Motor Lunch". By 1934, there were about 130 Pig Stands spread over 9 states. F
Around the same time, a World War I veteran learned about root beer and opened a small stand on a corner in Lodi, California. Within a couple of years, his stands expanded across California offering full carhop services and eventually began offering everything. Today it is known as A & W. The nice thing about drive-ins was they required less staff, less inside dining space, and often cost less. The drive - in became so popular that you could find one or more in most towns.
Other drive-in chains opened, some of which are still around today. One of the ones' I'm aware of is the Sonic drive-in which started in Oklahoma in 1953 as a root beer stand offering root beer, hot dogs, and hamburgers. Originally, he named his chain "Top Hat" but his lawyers informed him that name was already taken so he chose "Sonic". His drive-in differed from most others of the time because the parking spaces had speakers where people ordered their food which was delivered by carhops.
Then in 1948, just after the end of World War II, something new hit the scene in Baldwin Park, California. A small 100 square foot "In-n-Out" opened. In side there were five cooks who made meals for motorists who drove up, ordered, received and paid for their meals. It was not a drive-in, nor was it a sit down restaurant. It only cooked and delivered meals through a window and the driver didn't even have to shut down the car. Eventually the other major chains such as Jack-in-the-box, and Wendy's used the drive trough but McDonalds didn't adopt it until the 1970's.
As you noted earlier, the term carhop came because the first waiters would hop on the running board of a car. Females began replacing males as carhops beginning as early as 1931but by World War II held own a significant number of positions as carhops. Before 1940, it was standard practice for carhops to work only for tips while the drive-in would charge them for their uniforms but in California, the head of the Division of Industrial Welfare, ordered drive-in owners to pay the women minimum wage of $16.00 per week or face arrest. Many drive-in owners went to court over this demand because their workers were already earning between $25 and $70 per night and the judge granted the injunction the owners requested.
In Texas, carhops faced a totally different issue. Members of the public felt the carhops wore uniforms that were too short, too revealing, and much too indecent. This lead to many drive-ins changing uniforms from majorette outfits to proper blouses and skirts, or blouses and long pants. It was pointed out that carhops received better tips in the "skimpy" outfits than the new modest ones.
As more and more drive-ins competed for customers in the 1950's owners tried to speed up service by placing speakers for cars to order so the carhop would only deliver the food, to eliminating the service completely so customers had to walk up to the window, order the food themselves and walk back to their cars to building drive through windows which are used by so many customers in today's world. I hope you enjoyed this little bit of history. Let me know what you think, I'd love to hear. Have a great day.