Couples driving to dinner parties, neighborhood kids trick-or-treating, workers safely walking to their cars after a long day at the office: these are all activities made possible by outdoor lighting technology.
Throughout the 20th century, inventors and innovators developed new technologies to light our streets more effectively and create a safer, more productive society.
Incandescent lighting: moving past Edison’s bulb
Today, Edison’s famous carbon filament bulb still represents the concept of a good idea. However, during the 20th century, inventors were challenged with the task of making bulbs that were cheaper and more efficient than Edison’s original design.
At the start of the 20th century, developers needed a safer way to light streets than gas and fire-based streetlights, but they also needed an option that would last longer than Edison’s carbon bulbs. In addition, developers faced higher demand for safely lit streets as automobiles began to take off in America.
The first years of the 20th century saw competition between inventors to find the filament that would have the lowest cost and highest efficiency. In the 1910s, Irving Langmuir improved the design of the tungsten filament bulb by coiling the filament and filling the bulb with gas; the result was the most common incandescent light.
These tungsten-based incandescent bulbs were adopted as streetlights, and they made car travel at night possible in many major cities around America by the 1930s. During this time, Broadway, a famous street in New York City, earned the nickname Great White Way because of its abundance of lights.
Fluorescent lighting appears in outdoor applications
Even after tungsten filament incandescent bulbs became widely marketed and available, developments of other bulbs continued throughout the 20th century.
In the late 1920s, German engineers produced the first working fluorescent bulbs using phosphors, which convert invisible UV light into useable white light. These fluorescent bulbs were longer lasting and three times more efficient than incandescent bulbs.
After their introduction at the 1939 New York World’s Fair, the concept of fluorescent lamps as streetlights quickly rose in popularity. Fluorescents were an attractive outdoor lighting option because of their efficiency and novelty value. However, these lights were also large and fragile, and they produced a non-directional light. For these reasons, innovators moved quickly to develop new technologies for streetlights. However, fluorescent lights remain popular for parking lots building exteriors.
The search for efficiency: mercury vapor to LEDs
Although electric lights marked a huge shift in outdoor lighting technology, both incandescent and fluorescent bulbs lacked the brightness, direction, longevity and efficiency available in modern streetlights.
Despite the Great Depression, which hit the United States in the 1929, research for efficient bulbs persisted as lighting fixtures, along with oil, continued to sell.
While the 19th century saw quick developments in lighting technology, many 20th century lighting innovations represented maturation from previous designs.
These changes in lighting technology had a large impact on outdoor lighting throughout the latter half of the 20th century:
- 1959 – Gilbert Reiling developed lamps that used metallic salts to make a light with a more pleasant and neutral color.
- 1960s – Color-corrected mercury vapor lights were developed.
- 1962 – Reiling’s innovations resulted in the invention of the metal halide lamp, which would later be developed into streetlight technology.
- 1962 – Nick Holonyak, Jr., created the first visible-spectrum LED light using red diodes.
- 1970 – The high pressure sodium (HPS) light became a common streetlight. Known for its orange glow, the HPS is still used in many streetlights today.
- 1976 – Edward Hammer improved the fluorescent bulb by bending the tube shape into a spiral, inventing the first compact fluorescent light (CFL).
- 1980s-90s – Major developments in CFLs made them cheaper, longer lasting and more efficient.
- 1990s – The invention of the blue diode led to the advent of white LEDs. These LEDs are small, efficient and emit directional light. The developments allowed for the use of LED lights in traffic lights, flashlights and TVs.
By the end of the 20th century, LED lights became one of the fastest-growing lighting technologies. While LED lights are not yet widely used for outdoor lighting, that is starting to change due to their superior color, longevity and energy efficiency.
From the growth of electric streetlights to the invention of LEDs, lighting innovations from the 20th century continue to shape our world and light the way for the future.