Found a Minimum Speed Limit sign in the middle of my town.

You should check with the road authority because they might be fake.
One day I was driving down a road that I'd driven down many times when I spotted a new speed limit. It was posted in a weird location and the speed was odd.
I contacted the local main roads department and learnt that they didn't know about these signs. The next day they were gone.
- Agreed, having a minimum speed sign on a stroad is just begging for pedestrian deaths. It would be such an obvious liability that nobody in charge of transportation would allow it.
  
  Every municipality has a minimum speed limit so you can’t just have someone driving 1km/h down the road creating a rolling blockade. Most are posted on the entrance into the municipality.
  There are reasons for both sides to have and not have specific laws.
- Freeways/expressways around me are 45 mph minimum. They are normally mounted below the limit sign.
  https://www.twincities.com/2015/05/20/more-than-700-miles-of-interstates-in-wisconsin-to-be-70-mph/
  But I have seen small tack on signs that are the same in most regards.
  https://commons.m.wikimedia.org/wiki/File:SPEED_LIMIT_75mph_MINIMUM_SPEED_50mph_NO_TOLERANCE.png
- https://www.epermittest.com/road-signs/minimum-speed-limit
  Supposedly minimum speed limit signs do exist in California? No issue with checking anyway, I was curious is all
  
  40 is an example of the minimum on the interstate highway.
- That can't be common. And I've definitely seen minimum speed signs that persisted for years so I don't find them suspicious at all

Jesus. That Chevy is right up that guy's ass.
- Welcome to driving in America.
  Tbh I have no idea why so many people in this country tailgate. Do they not understand simple physics?
  
  A relative of mine rear ended someone and couldn't understand why they were at fault for the accident. Just kept saying the person in front of them just stopped out of nowhere and there was nothing they could do.
  People just don't realize they're supposed to give that much distance to the person in front of them. You're supposed to be able to stop without hitting the person in front of you if they, for any reason, stop without warning.
  In my area the driving manual only discusses stopping/following distances for the commercial drivers license, not the standard drivers license
- Based on the number of brake lights, either they're stopped, or about to be inside that prii's ass. Given the op didn't mention a crash, I'm going to guess traffic is stopped.
  Still too close, but makes more sense.

This is 100% to make the city unwalkable
- If you can't walk down a sidewalk with cars going by at 30mph then there's something wrong with you.
  
  30 mph is almost 50 km/h. In most of Europe the default maximum speed limit inside of populated areas is 50 km/h.
  Default meaning artillery roads like this one can and almost always do have higher limits than 50, but the defsult maximum suddenly becoming the minimum makes no sense.
  A road that isn't physically barricaded from foot trafic akin to a highway has no reason to have a minimum speed limit over 15 mph (30 km/h), if at all.
  
  30mph (48kmh) is the minimum, cars will also be going faster than that. Also, people need to cross the street, not just walk alongside it. Regardless, whether drivers or pedestrians are the issue, accidents happen. They are more likely to happen, and more likely to be fatal as vehicle speed increases.
  From the Institute for Road Safety Research, page 2:
  "According to an overview of recent studies (Rósen et al., 2011): at a collision speed of 20 km/h nearly all pedestrians survive a crash with a passenger car; about 90% survive at a collision speed of 40 km/h, at a collision speed of 80 km/h the number of survivors is less than 50%, and at a collision speed of 100 km/h only 10% of the pedestrians survive."
  Areas with minimum speeds of 30mph in areas with pedestrians accept that at least 1 in 10 will die. This is easily reduced to negligible fatalities by having lower speed limits. Not doing so says we care more about saving some of the drivers' time than the lives of pedestrians.

I know here in Brazil there's a minimum speed limit on highways of 50% the max, but there are no signs, and it doesn't apply in heavy traffic.
- In Denmark we have a single piece of highway were we have a "crawl lane". It's slightly uphill and outside the lane you must go at least 80km/h. I know it is more common in Southern Europe.
  
  Here in Germany, the Autobahn has a minimum speed cars need to be able to go (60 kph) although it’s not a minimum speed you necessarily need to drive.
  However, we do have a dedicated minimum speed sign, but it’s very rare and usually only used in very specific places. The only one I know is a long and windy bridge on the side of a small mountain where, depending on your lane, you need to go at least 60, 80 or 90, I think.

Sorry for running over your child, ma'am, but rules are rules.

slow down to stop at traffic signal
car explodes like in speed

Lots of white knuckled old people and nervous drivers.

That has to be a misprint or a photoshop. There is zero chance of a minimum 30 mph (or kph) inside city limits, especially with a perpendicular entrance/exit right there.
- Maybe the installer didn’t notice it said minimum haha
- Not photoshop, you can go there and see it.
  
  WHERE

Amish country in PA?

I've seen signs like that on the bridge from Virginia to Maryland. It makes sense though, it can be very dangerous with a large speed differential on that particular bridge. It's kind of a scary bridge. My ex-wife refused to drive on it.

No Ghost Riding the Whip

Lol, so... You can't stop?

Pretty good shot for going that fast
- Speedwalking on the sidewalk has never been more fulfilling.
  
  Ok Usain.

Maybe there’s a local problem with cruising for prostitution?
- I see your logic and had the same thought, but then wouldn't a "No stopping at anytime"/"No parking" sign accomplish the same thing? "No Loitering" sign as well. If the point is for the cop to be able to point to a sign, those already exist and are much more broad and easy to use(or misuse, depending on your perspective). Like others said, an absolute minimum speed limit seems destined to harm pedestrians. Plus, you can see it's before a stoplight. So not even logical.
  I'm betting this is a fake sign.