This visualization shows the median sales price of houses in Massachusetts over time, broken down by the number of bedrooms. The theme river displays the changing price levels for houses with two, three, four, and five bedrooms across quarterly data from 2007 to 2019. Using the D3.js library, the code processes the CSV data with `d3.csv` and renders the streamgraph as an SVG. The plot uses stacked, colored bands to represent each bedroom category, revealing relative price trends and fluctuations across the housing market.