A force-directed network diagram maps six Texas cities as movable nodes connected by route edges. The SVG visualization uses `d3.forceSimulation` with link, charge, and centering forces to position the graph, while nodes are rendered as blue circles with city-name text labels. The code implements dragging via `d3.drag`, updates positions on each simulation tick, and uses `data.forceLink` to bind node IDs to the specified city-pair relationships.