Pretty sure it's Helvetica.
If you have photoshop or some program like that, use Bell Gothic Std and increase the vertical scale to %130.
The "S" in Bell Gothic Std doesn't look the same as the stop signs in St. Louis (and there are thousands of them). So far the closest font I've found is ITC Avant Garde Gothic (Medium Condensed).
Found it! Roadgeek 2005 Series C is a perfect match. Get it here: http://www.triskele.com/index.html These are freeware fonts, created by Mike Adams and based on all of FHWA Series B through F, plus additional fonts based on highway signage around the world.
Most municipal/government organizations use Helvetica for public signs. It is also the most widely used font in advertising.
For interpretive displays and publications, the sans-serif title font is Frutiger and the text font is called NPS Rawlinson.
Stop signs.
Stop signs
I believe the "... the good life" part is Bauhaus. I'm still trying to figure out the "NEBRASKA" font.
The font used for signs in Bioshock Infinite is called "Nashville." It is a clear, vintage-style typeface that fits well with the game's early 20th-century setting in the floating city of Columbia.
Stop signs and Warning/Guiding signs. You must make a complete stop at a stop sign BEFORE the solid white line.
Stop signs
Stop signs are attached to either wood or metal poles. Stop signs may also be attached to a school bus to be used when students are loading or unloading.
There isn't a specific height for a stop sign, I've seen short stop signs, tall stop signs, etc. Taller stop signs would probably be in areas where there's high traffic so everyone can see them, the shorter stop signs are used in parking lots.
stop signs, 50cent
There are a wide range of road signs that are used for various reasons. There are stop signs to warn people to stop at intersections, Yield signs so that one will yield to oncoming traffic, Deer Crossing signs to warn of areas where there might be deer crossing the road as well as Speed Limit signs to warn drivers of the allowed speed in a designated area.