Those of you born after 1990 or so have grown up in an automotive world where "all cars" have composite headlamp assemblies, uniquely designed to be make- and model-specific. If a light within the assembly burns out, you replace "just" the bulb. If the unit cracks, you must purchase a replacement that fits your car and your car only.
This was not always the case! For approximately 45 years, all U.S.-specification cars were required by law to use "sealed beam headlamps". What are they? They are a headlamp assembly consisting of an enclosure with a bulb in front of a lens, completely made of glass. The entire unit is sealed (hence the name) and none of the parts can be replaced separately. If the headlight stops functioning or breaks, you replace the entire sealed beam light (they were, and still are, rather affordable). Replacement lamps guaranteed to fit your car were available in every auto parts store.
Sealed Beam Headlamps Timeline
As difficult as the following may be to believe, the U.S. government used to be very strict about dictating both the size and shape of sealed beam headlights fitted to vehicles sold in the United States. Needless to say, this imposed some limits on car design. They were not without their advantages for the consumer, though. Made of glass, the outer lens did not become dull or opaque from exposure to the elements the way some plastic lenses do. Every time you replaced a headlight, you got a new lens. The actual replacement was quite easy to perform on most cars.
Let's go back and walk through a timeline of those years when all cars used sealed beam headlamps.
PRIOR TO 1939: Headlamp design was not standardized. While many cars during the earliest part of the 20th century used round, stand-alone lamps, as car design evolved, auto manufacturers began to design lamps unique to their vehicles.
1940-1956: To control chaotic supply problems with unusual headlights, all U.S. cars were required by law to use (2) 7" round sealed beam headlamps with one lamp on each side of the vehicle. Note that each lamp is a "dual filament", meaning that the same sealed beam lamp serves as both low beam and high beam. Therefore, they all have 3 electrical prongs at the rear.
1957: The U.S. law changed, and began to allow the use of FOUR sealed beam headlamps, each lamp measuring 5 3/4". Two would serve as the low beam, and two as the high beam. Each lamp has two electrical prongs at the rear. American carmakers quickly began to transition from 2-headlamp designs to 4-headlamp designs.
An interesting example of the headlight switchover was the 1957 Mercury. While many high-end makes began their 1957 model year run using 4 headlights, Mercurys did not. Stylists decided not to wait until the 1958 model year to switch to a 4-headlight setup. As a result, 1957 Mercurys ended up being built in both 2-headlight and 4-headlight versions.
1958-1975: With 4 round lamps now legal, the majority of American cars adopted them. Note that the 2 lights on each side could be arrayed horizontally, vertically, or diagonally. Still, some vehicles continued with 2 lamps.
Many 1960s era cars had their 4 headlamps arranged horizontally (1961 Chevy), vertically (1963 Pontiac), or diagonally (1962 Chrysler).
A 1964 Ford Mustang used 2 round headlamps, and Mustangs continued to do so for most of the 1960s and 1970s.
1975-1984: U.S. law changed again, and allowed the use of rectangular headlamps. Two-lamp systems (low and high beam in same bulb) used 200mm size lamps. Four-lamp systems (separate low and high beam lamps) used 165mm size lamps. Note the switch to a metric measurement. Also, while rectangular lamps were permitted, they were not required. By the late 1970s, most American cars had switched to rectangular lamps, although a few stayed with round lamps.
Compare the 1974 (LEFT) and 1975 (RIGHT) Chevy Monte Carlo; the only principal styling change is the switch from round to rectangular (vertically stacked) headlamps.
1984-PRESENT: The U.S. law changed and allowed composite headlamp assemblies with replaceable bulbs for the first time. The first vehicle with these lamps was the 1984 Lincoln Mark VII. Nevertheless, some lower-priced vehicles, and cars with hidden headlights, continued with the less-expensive sealed beam headlamps. For example, Mazda Miatas up through 1997 used 7" round sealed beam lamps.
Further taking advantage of the change in regulations, some car manufacturers built cars with rectangular lamps in sizes other than had been previously allowed. Your car or truck may have a "small" rectangular lamp that actually measures 92x150mm, or 55mmx135mm. If shopping for a replacement lamp, it pays to take measurements first.
For styling reasons, by the early 1990s, the majority of American automobiles made the switch to composite headlight assemblies. For the European and Asian imports, it was simply a matter of reverting back to their "home market" headlamps. It’s interesting to note that while all cars sold in the U.S. ditched sealed beam headlights a while ago, some base-model commercial vehicles continued to use them in their least-expensive variants through the 2017 model year. Today, there are no new cars or light trucks sold with sealed beam headlights in the United States.
Replacement Sealed Beam Headlights
If you need new sealed beam headlights for your vehicle, don’t worry if you don’t know the size measurements offhand. Just use the “Select Vehicle” field at the top of the screen to enter your year, make, and model – then hit “go”. Once your car's information is provided, our website will automatically narrow things down to the choices that will fit your specific vehicle.
Sealed Beam Headlight Units With Updated Features And Modern Styling
If you’ve got a classic vehicle with round or square sealed beam headlight units, odds are you like the styling of the vehicle and want to keep the overall appearance stock. But some days, you might find yourself wishing for headlights that put out more light. Or you might feel you’re missing out on the chance to customize your headlights with attractive styling variations found on modern composite headlamp assemblies.
You’ll be happy to know we’ve got custom sealed beam headlight units that offer all these advantages. These “plug-and-play” units install in place of your original headlights quickly and easily without modification, and are available in all traditional round and square sizes. As you browse through our selection, you’ll be impressed with designs that feature projector lenses, halo rings, and built-in brilliant LEDs that make your path brighter at night – all while turning heads in amazement.
We hope you’ve found this article interesting and informative. We also want to say if any of the headlights we offer have piqued your interest, we have knowledgeable reps on call seven days a week that can give you more details and answer any questions – so give us a ring!