Which map describes the movement of people, trends, or materials across a physical area?

A flow-line map effectively illustrates the movement of people, trends, or materials across a specific physical area by using arrows or lines to depict the direction and volume of the flow. This type of map visually represents movement and can indicate where people migrate, trade routes, or the distribution of resources. The thickness of the lines can indicate the magnitude of movement, while the arrows provide a clear indication of the direction.

Other map types serve different purposes. A political map shows boundaries, locations of governmental units, and major cities but does not convey movement. A cartogram distorts the size of geographic regions based on a particular variable, such as population or economic data, rather than illustrating physical movement. A qualitative map displays various characteristics or qualities of an area but does not specifically focus on the flow of people or materials like a flow-line map does. Thus, the flow-line map stands out for its specific emphasis on movement and trends.