Answer:
The phrase "thickening late afternoon crowds" likely describes a scene or situation where the number of people or vehicles in a particular area are increasing as the day progresses. It could refer to a crowd of tourists or visitors at a popular attraction, or to the increase in traffic on a road or public transport hub during rush hour. In general, it implies that there is a gradual buildup of people or activity over time, especially in the late afternoon or early evening.