What is a warning sign that indicates a merger ahead?

A yield sign is specifically designed to inform drivers that they should prepare to slow down and yield the right-of-way to merging traffic. This sign is typically placed in locations where a road merges with another or where two lanes of traffic come together. The yield sign alerts drivers to the possibility of vehicles merging from different directions, allowing them to adjust their speed and position on the road accordingly to ensure safety.

In contrast, a stop sign requires drivers to come to a complete stop, which is not appropriate for a merging situation where continuous traffic flow is needed. A curve sign indicates a change in the road's direction, warning drivers to proceed with caution but does not specifically relate to merging traffic. A crosswalk sign indicates pedestrian crossing areas, which is unrelated to the concept of merging vehicles. Thus, the yield sign is the most suitable indicator of an upcoming merger.