This interactive network visualization displays a conceptual city flight route network, with seven cities colored by regional group (East, Central, West) and nine connecting routes. The layout is driven by a physics-based force simulation using `d3.forceSimulation` with `d3.forceLink`, `d3.forceManyBody`, and `d3.forceCenter` forces. Nodes are rendered as SVG circles with city labels, and users can drag nodes to reposition them, which dynamically updates the simulation. The explicit node and link data are defined in arrays within the code.