This interactive line chart compares daily high temperatures in New York, San Francisco, and Austin, with each city rendered as a steel-blue path. The chart uses D3.js v3 with `d3.time.scale` for the date axis and `d3.scale.linear` for the temperature axis, while `d3.interval` and `d3.svg.line` draw the smoothed curves. The data is embedded as a tab-separated string, parsed via `d3.tsv.parse`, and colors are assigned using `d3.scale.category10()`. A legend and mouse-over effects are included to highlight the selected city's values.