Sirens and lights atop law enforcement automobiles is no new thing but the type, color and shape of police car siren sounds, lights and cop cars themselves have changed quite a bit over the years. Don't forget, too, that other countries have different laws about police car siren use and appearance. There is a lot of variety in the visual and auditory signs people associate with police.
Perhaps the two most recognizable signs of a police presence is those loud police car siren wails and the flashing lights. The type of light used to send up the emergency symbol has changed as technology has improved. In the beginning, the simplest of light bulbs were used. Just as modern technology in other areas far exceeds the developments of 100 years ago, today cop cars use the latest LED technology for their flashers.
The United States has long had red, white and blue emergency vehicle lights though when used and how they are powered has changed. Amongst other countries, red and blue are also popular colors for emergency services. Some countries, however, specifically prefer blue. In many parts of Asia, however, red is the color of emergency vehicle lights.
The remote police car siren has been part of law enforcement for many years. In the very beginning, when automobiles were first being used by the police, none of them have roofs! Later, canvas covered models became available and were used. It was in the 1930s that cars started to have enclosed tops and that is when the look of the modern cop car was born. Of course, all of these decades of cars had sirens to alert the criminal and the surrounding citizens of an emergency.
In the early days, all car including police cars had running boards. A running board is a platform between the back and front wheel on each side of the car that serves as a stepping surface for passengers getting in and out. In the 1940s, after World War Two, most cars being made had sleek raised wings on the hood and so cop cars of the day did as well.