This line chart displays multi-year budget estimates for Block IV SSN submarines, with each line representing a different submarine class and its projected delivery dates. The visualization uses D3 v5 with SVG rendering, employing `scaleTime` for both axes, `scaleOrdinal` for color mapping, and a `line` generator with `curveBasis` smoothing. A color legend is built using a custom `colorLegend` function, while the data is sourced from Data Canvas - Sense Your City and processed via D3's `nest` and `descending` sorting to order the lines.