This is the marker used on state scenic highways in California.
<ul><li><b>Original: </b> <a href="https://en.wikipedia.org/wiki/California_Department_of_Transportation" class="extiw" title="w:California Department of Transportation">California Department of Transportation</a></li>
<li><b>Vectorization: </b> <a href="//commons.wikimedia.org/wiki/User:Master_son" title="User:Master son">Master son</a></li></ul>
2008-01-31
<a rel="nofollow" class="external free" href="http://www.dot.ca.gov/trafficops/tcd/docs/G30A.pdf">http://www.dot.ca.gov/trafficops/tcd/docs/G30A.pdf</a>