This map visualizes H1B petition locations across the United States, with each city represented by a circle colored according to the petition year. An interactive legend on the right allows users to highlight petitions from a specific year, dimming all other circles. The visualization uses React with D3 v5 for map projection via `d3.geoPath` and `geoAlbers`, while `scaleOrdinal` maps years to colors. US state shapes come from the US-Atlas TopoJSON, and the petition data is loaded from a CSV file.