This interactive map visualizes the distribution of motor-vehicle collisions across New York City, with each crash represented as a point on a geographic grid. The code uses D3.js's `d3.geoPath` to render city boundaries and `d3.select` with a custom color scale to encode crash density by neighborhood. Data is loaded from a local CSV via `d3.csv`, and the rendering relies on the Canvas API for efficient point plotting. A brush interaction, implemented through `d3.brush`, allows users to filter collisions by time of day or day of week, dynamically updating the displayed points.