Most Drive-In Movie Theaters consist of a large outdoor screen (either a wall painted-white, or a complex steel-truss structure with a complex finish), a projection booth, a concession stand and a large parking area for automobiles. Within this enclosed area, customers can view movies from the privacy and comfort of their cars.

Drive-in Theatre Patent Drawings.
The idea originated in the early 1930's in Camden, NJ. and was Patented by Richard M. Hollingshead. His idea began as an experiment in his driveway with a Kodak Projector, mounted on the hood of his car, aimed at a screen that was attached to some trees. He tried different techniques and finally worked-out the parking-arrangement and spacing to allow everyone that attended, an unobstructed view of the screen. Once he had this idea in- place, he was granted a Patent in 1933 and He opened his first Drive-In Theater soon thereafter. This facility only lasted a few years before closing, but the idea caught-on elsewhere to become part of the American Pop-Culture and Landscape to-this-day.

Typical-style of Drive-In Theater Speakers with the Volume Knob.
Sound was originally produced from Speakers in the main screen tower, but the quality wasn't that good and many attempts were made to improve it. In 1941, the RCA corporation found a solution and along-came the in-car speakers with built-in volume controls that most drive-in patrons would come to know. These were better than the original Sound, but still had a very "tinny" sound to them. Later-on, as the technology improved, this system was replaced with Radio Broadcast equipment to allow the sound to be transmitted directly to the vehicles. This was an improved process for sound and also kept damage to the wired Speakers and/or patrons cars that would happen when folks would leave, after a good show of their favorite film, and some people would "forget to remove the speaker" and damage both the speaker and/or their cars in the process (i.e. Windows, or scratches/dents, etc.).
The popularity of the Drive-In's soared after World War II and peaked in the 1950's and 1960's. The theaters would provide cheap, family entertainment including many having a Playground (or other things) for their youngest patrons. For colder-weather, in-car heaters were also offered at many Theaters, much like the Speakers had been.

This type of heater plugged in to 120vAC (not 12V car power)
to warm your car during cold nights at the drive in movie.
The Concession Stand (or Snack Bar) would have food that could be served very quickly. Hot Dogs, Pizza, Cheeseburgers, Popcorn, Soft Drinks, and a host of other "food" could be found there to enjoy along with the show. This is usually where the Theater makes most of it's profits and much of the promotions are geared towards that area.
An "intermission cartoon" to entice patrons to the Concession Stand.
This was vital to the success of drive-ins, as food revenue increased steadily during the late 1940s and 50s. While some operators experimented with talk-back speakers to take orders and deliver food to the car, others had mobile carts patrolling the lots selling snacks. Over time, owners discovered that concessions could be sold at a high mark-up and that revenues did not have to be shared with film distributors.

Another Intermission Ad
To this day, food revenue remains extremely important to exhibitors, especially with film rental rates going as high as 80% on opening weekends for some features. In order to promote the concessions, most locations used the now-famous drive-in intermission films, popularized by the Filmack Company, featuring dancing hot dogs and countdown clocks that were supposed to mesmerize the audience members, wet their pallets and open their wallets.
Many Theaters even had "car-hops" like their Drive-In Restaurant counterparts to make the experience even more appealing for their patrons.

A car-hop, much like a drive-in restaurant.
The Drive-In owners would later allow other-uses for their large amounts of space which could only be used for the Theater after-sunset. This would usually generate more income for the theaters and some of these uses included Flea Markets, Swap Meets, and even Outdoor Church Services.

A typical Flea Market at the Mission Drive-In, San Antonio, Texas, 1984
Over time, with the advent of other sources of entertainment, as well as the rising cost of Real Estate and other economic factors, Cinematic Landmarks such as these have been slowly disappearing over the years, leaving less than 500 across the United States currently. Many of those which were closed were later demolished and the real-estate used for other things such as Office or Retail Space, with some being replaced on the exact same land with Mutli-Plex indoor Movie Theaters. Some properties have just been left vacant with nothing remaining there but an empty field. However, a very-select few that were closed have even re- opened to be given a new-life with new patrons looking for a very unique movie-going experience.
Many folks feel that these Gems of Americana are very much an endangered part of the landscape. Most, if not all of them, have very fond memories of their time spent there and would love to be able to revisit their favorite Drive-In Theater once again.

Michigan Cinema History:
The Compuware Drive-In Theatre
Beck Road, Plymouth, Michigan
OPEN: 2004 | CLOSED: n/a | CAPACITY: (est.) 500

One of the temporary screens for the drive-in
The Compuware Drive-In Theater is one of the most recent additions to the Drive-Ins of the Metro area, and is also one of the most unusual because of it's location within the complex of the Compuware Sports Complex parking Lot. It is also unusual because of the fact that as of 2017, it was the only other active Metro Detroit Drive-In Theater aside from the Ford-Wyoming, in Dearborn.
The Compuware Drive-In opened in the spring of 2004 with much fanfare, with TV and radio coverage and both major newspapers covering the opening extensively. The result was a more than sold out night with an at-capacity attover 500 cars!
The screens are "temporary" in nature, and the size is approximately 40x80 feet, and are about approximately 20 feet off the ground to compensate for the lack of ramps which normally would be in a typical Drive-In Theatre for improved visibility (line of sight) to the screen.

Close-up of one of the temporary screens : 2007
The pricing at the snack bar was typical for any theatre, maybe a tad higher (4 dollars for a hamburger). The selection was pretty good, burgers, dogs, sausage with the movie staples of popcorn and candy and pop. The much discussed restroom situation was better than expected. Although they are portable, they were heated trailers with hot water and regular stalls.
The screens themselves may eventually be permanent, but the projection booth, concession stand, and ticket booth are not because of the variety of events held at the complex. There was plenty of security and folks directing the cars to their parking spots and are lined-up by the use of white lines painted on the pavement. The yellow lines being used for for regular parking for the facility. There was, understandably some confusion amongst some of the patrons as to the proper space and position for their vehicles.

The "Ticket Booth" for the Compuware Drive-In
The picture quality was decent, it was sharp and quite bright with a small amount of light pollution visible from the nearby businesses in the area. This minimal amount of light did not adversely affect the images on the screens. The sound was broadcast through FM radio and was good although there was a small amount of interference at times. There was also a short vintage intermission reel between movies to provide a bit of nostalgia for the attending patrons.
The original plan was to run at least 3 screens for Theatre use thru December, then close down until March, usually the coldest and least-desirable months to sit outside even in a vehicle, to watch a first-run flick. There has been much interest in the concept from other arenas and stadiums around the country to do something similar.
The Theater did fairly well in its initial few years, but interest in it has declined some during the time it's been open.
It has been mentioned that the resurrection of the Drive-In has provided some good memories to those folks that had maybe heard of these type of facilities, but never been able to experience a "real" drive-in before.

This one, like many of the Drive In Theaters that are no longer around, are a wonderful piece of Endangered Americana that are missed by all who treasured the times that they had there.
IF you have any good-memories or stories of this, or any other Drive-Ins, please feel free to share in your logs.
Enjoy the Hunt...and beware of your surroundings, as always. :)