In short
On the US road test, the routine is Mirror → Shoulder Check → Signal → Manoeuvre. A missed shoulder check before a lane change is the single most-scored road-test fault.
Updated 2026-06-06 · 5 min read · By Driving Routes Editorial
Why the shoulder check matters
Your blind spot is the area not visible in any mirror. For a typical sedan, it's the rear corners on each side — exactly where a car merging into your lane could be.
US examiners specifically watch for the over-the-shoulder check before any lane change. A mirror-only check is a fault.
When to apply it
Every lane change, every change of direction, every move off from a curb, every freeway merge.
Frequently asked questions
Do I have to signal every time?
Yes, in the US. Signaling at least 100 feet (or 5 seconds) before a turn is required by law in most states.