I am looking for a place to live in the Seattle metro area. I care about three things: price, how long it takes to drive to my office, and how close the nearest climbing gym is. So I mapped every residential home sale in King and Snohomish County from the last twelve months and built an interactive tool to explore them.

The map below shows 32,490 sales. In hex view, neighborhoods are colored by median price — green is below the overall median ($860K), red is above. You can toggle to individual points, filter by bedrooms, price, square footage, year built, and maximum drive time to my office (Microsoft Building 43) or the nearest climbing gym. Drive times are traffic-aware, modeled for a Tuesday morning commute via the Google Maps Distance Matrix API.

How it works

The data pipeline pulls sales records from the King County Assessor and the Snohomish County Recorder, geocodes each parcel via their respective ArcGIS APIs, and enriches the data with building characteristics (bedrooms, square footage, year built). Sales are assigned to H3 hexagonal grid cells for the neighborhood view — each hex covers roughly two city blocks.

For drive times, I used a two-tier approach: hex centers at a coarser resolution (~1 square mile) are sent to the Google Maps Distance Matrix API with a Tuesday 8 AM departure time. This produces traffic-aware estimates that are significantly higher than free-flow routing — a difference that matters when you are deciding between a 15-minute commute and a 35-minute one.