This multi-line chart displays monthly average temperatures for four U.S. cities—NYC, LA, Chicago, and Houston—with each city represented by a colored line and corresponding data points, parsed from a CSV file that includes degree symbols. The visualization uses D3 v7 with SVG rendering, employing scales for positioning data across the months, drawing paths via the `d3.line` generator, and adding interactive tooltips on hover that display the specific city and temperature for each month.