So I was riding through Bay City one day and we passed the Michigan State Police post there.  As I gazed over the cars, the most striking thing was that each of them had a ‘fin’ on the hood:

I was curious what it’s function was, so I wrote an email to the state police through their website:

I have a question that’s more of a trivia question than anything else.

What is that placard/fin thing on the front of the car for? The one that says ‘state STOP police’. I’ve never seen it used, and it seems like if you
were close enough to read it you’d be already stopped anyway. Most traffic stops I’ve seen would render the thing not visible behind the cabin of the car.

Does it have a name? How is this used? Is it there mostly for tradition?

So I got a response today!

Hi David.

The MSP Webmaster forwarded your message to me.

I’m a retired MSP inspector, and serve as the department’s “unofficial” historian. I now work as an outreach specialist in the MSU School of Criminal Justice. By the way, my wife is from Midland–her Dad worked for Dow many years ago.

I get a couple of questions a year on this specific issue about the patrol cars.

The “STOP–State Police” placard on the hood of MSP patrol cars goes back to the late 1920s when the department used Harley-Davidson motorycles on patrol, just before we bought our first fleet of marked patrol cars (Ford Model A’s in 1929).

The department installed small “State Police” placards atop the front fenders on the bikes so troopers making side traffic stops (the bikes had no
red lights) could pull up next to the driver door of a car, and the motorist could see the State Police sign and pull over. The MSP uniforms were a very plain black design at the time, so even the uniform did not make it obvious that it was a trooper. The MSP quit using motorcycles in 1942, during the war, but brought them back on a limited basis in Detroit in about 1993.

We didn’t use placards on patrol car hoods until 1954 when they switched from the old black color to the bright new blue color and gold door shield with lighting bolts still used on MSP patrol cars today.

At that time, since MSP still did blockades (pulling across predesignated places on major roads to stop and check cars following major crimes), and also did side patrol stops with the cars, they thought the plexiglass “STOP–State Police” placards would help make the cars more visible and
identifiable as MSP cars. The placards are also lighted in the mounts at each end, to improve their visibility at night, and help identify the cars
when troopers would pull into someone’s driveway at night on an investigation. We troopers often did not turn them on, because we also
feared it made us a better target!

MSP quit teaching side stops to troopers and ended the blockade system as impractical back in the early 1980s. Thus, the placards really have no
practical use today. The head of the state Motor Transport garage called me about ten years ago asking for my support to propose to MSP that they drop the placards. They are very expensive to buy and install, and a real pain for the mechanics who have to prep new patrol cars.

I raised this issue with HQ, but was told politely to forget about it–theyhad become a traditional feature of MSP patrol cars, and so they would stay!

Phil Schertzing, Ph.D.
School of Criminal Justice
Michigan State University

This was an AMAZING answer!  I am shocked at the effort put in by Dr. Schertzing in formulating this response.   Now that I know the story behind the placards, I love the fact that they’re on the cars to this day.  It’s like an appendix for their cruisers or something!

A couple more pictures of some most excellent placards – a 1958 chevy and a new dodge charger:

Simply splendid.