When did the speed limit on this road change?
<p>Here is a diagram of a section of road I drive on to work (traveling top-to-bottom)</p>

<p><a href="https://i.stack.imgur.com/7X3zK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7X3zK.png" alt="enter image description here"></a></p>

<p>The last sign on my way out of town (shown in the top left of the picture) says "SPEED LIMIT 45".  A couple of miles later, there are two signs on my left (facing the oncoming traffic).  If I turn my head I can see the "REDUCE SPEED AHEAD" and "SPEED LIMIT 45" signs.</p>

<p>That indicates that people coming into town must slow down to 45.  No surprise there - they were traveling for miles on this rural road at 55 MPH and now need to reduce speed entering town.  So that's an indication that at some point I can speed up to 55 driving <strong>away</strong> from town.</p>

<p>But when does that happen?  There are no "SPEED LIMIT 55" signs in my direction once I leave town.  How long is the final "SPEED LIMIT 45" sign in my direction in force before I can speed up to 55?</p>

<p>It is important to be certain about where that point is, because insufficient speed can earn you a ticket just as excess speed can. <a href="https://www.ncleg.net/EnactedLegislation/Statutes/HTML/BySection/Chapter_20/GS_20-141.html" rel="nofollow noreferrer">GS 20-141</a> makes it illegal to drive below 40 MPH in a speed zone of 55 MPH. However, if there is no posting of minimum speed, that restriction does not apply.</p>

<p>Under state law, the maximum speed limit is 35 MPH inside municipal corporate limits, and 55 outside corporate limits. DOT can raise or lower limits depending on whether they find that faster is still safe or the statutory limit is too fast, but the limits must be posted.</p>

<p>The municipality may have taken advantage of para (e)</p>

<blockquote>
  <p>Local authorities, in their respective jurisdictions, may authorize by
  ordinance higher speeds or lower speeds than those set out in
  subsection (b) upon all streets which are not part of the State
  highway system; but no speed so fixed shall authorize a speed in
  excess of 55 miles per hour. Speed limits set pursuant to this
  subsection shall be effective when appropriate signs giving notice
  thereof are erected upon the part of the streets affected.</p>
</blockquote>

<p>Or, para (f)</p>

<blockquote>
  <p>Whenever local authorities within their respective jurisdictions
  determine upon the basis of an engineering and traffic investigation
  that a higher maximum speed than those set forth in subsection (b) is
  reasonable and safe, or that any speed hereinbefore set forth is
  greater than is reasonable and safe, under the conditions found to
  exist upon any part of a street within the corporate limits of a
  municipality and which street is a part of the State highway system
  (except those highways designated as part of the interstate highway
  system or other controlled-access highway) said local authorities
  shall determine and declare a safe and reasonable speed limit. A speed
  limit set pursuant to this subsection may not exceed 55 miles per
  hour. Limits set pursuant to this subsection shall become effective
  when the Department of Transportation has passed a concurring
  ordinance and signs are erected giving notice of the authorized speed
  limit.</p>
  
  <p>When local authorities annex a road on the State highway system, the
  speed limit posted on the road at the time the road was annexed shall
  remain in effect until both the Department and municipality pass
  concurrent ordinances to change the speed limit.</p>
</blockquote>

<p>Once you are outside the corporate limits, the corporation has no authority to modify the limits set by the state, and the state limit of 55 is applicable. There is no requirement to the effect that the corporation must tell you that you may now result your regular speed. It would be polite, but not legally required.</p>

united-states traffic speeding north-carolina