No Standing Any Time Sign
MUTCD R7-4
You may not stop here to wait or to pick up or drop off passengers at any time; both standing and parking are prohibited.
What it looks like
A vertical white rectangle with black legend reading NO STANDING ANY TIME, sometimes with a directional arrow.
When you'll see it
Posted along curbs near intersections, transit stops, and loading zones where a waiting vehicle would obstruct traffic or sightlines.
What to do
You must not stop here to wait or to pick up or drop off passengers at any time; both standing and parking are prohibited.
Related signs
Source: Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition — FHWA.