Following distance — Missouri Permit Test
Following distance on the Missouri permit test — 6 rules, each with the reason behind it and a question on it while it is fresh.
The rules
A good way to measure your safe following distance is the three second rule.
Distance in car lengths changes with speed. Distance in seconds does not, which is why the rule is a count.
A good way to measure your safe following distance is to use the “three second rule.”
To use the three second rule, choose an object near the road ahead and start counting as the vehicle ahead of you passes it.
The object is a fixed point both cars pass. That is what makes the count a measure of distance.
Choose an object near the road ahead, like a sign or telephone pole. As the vehicle ahead of you passes it, count slowly
If you reach the object before you finish counting, you are too close to the vehicle ahead.
The test gives you an answer rather than an opinion, and the answer is either yes or no.
If you reach the object before you finish counting, you are too close to the vehicle ahead.
Rear-end crashes are very common, and are caused by drivers who follow too closely and cannot stop in time when the vehicle ahead suddenly stops.
The most common crash has the simplest cause and the simplest fix.
They are caused by drivers who follow too closely and cannot stop in time when the vehicle ahead suddenly stops.
Stopping distance equals reaction distance plus braking distance, and the chart's reaction distance allows one and one-half seconds.
Most of a short stop is the time before the brake is touched at all.
In the chart shown below, the reaction distance is for 1.5 seconds.
If you are driving fast, are very tired, or your vehicle has bad brakes, you will need more space to stop.
Three different things lengthen the same distance, and two of them are about you rather than the car.
If you are driving fast, are very tired, or if your vehicle has bad brakes, you will need more space to stop your vehicle.
On the test
What does the guide call its measure of safe following distance?
The three-second rule. Distance in car lengths changes with speed. Distance in seconds does not, which is why the rule is a count. Missouri Driver Guide, p.57: “A good way to measure your safe following distance is to use the “three second rule.””
How this works
Most practice tests hand you a bank of questions and leave the manual somewhere else. This one puts them together.
You read one law and the reason behind it, then answer a question on that law while it is still fresh. Get it right and you move on; get it wrong and you have found the gap while it is cheap to fix, not on the morning of the exam.
Learning one rule at a time, and proving it immediately, is what turns a manual you skimmed into something you actually know — and it makes studying feel like getting somewhere rather than like waiting to find out.
What it costs
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Where these come from
Every rule here is checked against Missouri Driver Guide, published by the Missouri Department of Revenue, and against the state code itself. Last checked 2026-09-16.
- src/assets/drivers-manuals/MO.pdf (Missouri Driver Guide, Revised August 2026, retrieved 2026-09-14)
- src/assets/drivers-manuals/MO.pages.txt (plain pdftotext over that PDF; sha256 pinned in SOURCES.json)
- src/assets/drivers-manuals/SOURCES.json (sha256, folio offset 2, folioMarker, nonLawPages and the extraction flag, each with its measured basis)