Over the past year, our data team has worked with the OpenStreetMap community to do a full import of building footprints released as part of New York City’s open data initiative. The result is over 1 million new buildings and over 900,000 new addresses — adding value to OpenStreetMap, creating more context, and making the map more searchable. The data has been continuously available on Mapbox Streets within minutes of each edit.

Progress animation showing the import of one million new buildings and addresses in New York City to OpenStreetMap.

Imported buildings contain height information (full map).

Along with buildings, we imported over 900,000 addresses — as seen here in the Park Slope neighborhood of Brooklyn.

OpenStreetMap as a platform for data collaboration

From the beginning, one goal of this huge data import was to help the city government maintain its building and address datasets: edits on OpenStreetMap are a signal that the ground truth may have changed. Today, the New York City GIS department subscribes to daily email notifications of building and address changes in OpenStreetMap, indicating where updates in the original dataset are necessary.

Excerpt of the daily email notification going out to the New York City GIS team, showing changes to buildings and addresses.

Import process

OpenStreetMap’s biggest asset is data integrity informed by local knowledge. Hence, the top priority for the data import was to ensure highest quality and to preserve local knowledge. To this end, we involved local community from the start and ensured import quality by following OpenStreetMap’s import guidelines, making data conversions repeatable, distributing jobs with the Tasking Manager and by using Github to track import issues.

We have not only added data, but fixed existing map errors where possible. For instance, mappers involved in the import have added 959 layer tags to bridges and have realigned over 4,000 points of interest such as schools, fire stations and restaurants with building boundaries.

For a full rundown of the import process, read up on my in-depth post over on OpenStreetMap.org.

Continuously improving the map

We are not done yet. While all data has been imported to OpenStreetMap, there are final cleanup tasks we are tackling at the time of this post. Help us further improve the map: if you find a building or address related issue on the New York City map, please let us know by filing an issue on Github. As soon as new data is available from New York City, we will also take a look at updating OpenStreetMap where it makes sense.

Huge thanks to all contributors outside of the Mapbox team who have helped make this import happen. Through your work reviewing, coding, coordinating and doing data uploads you have helped make this import better than it would have been without you: Serge Wroclawski, Eric Brelsford, Liz Barry, Toby Murray, Ian Dees, Paul Norman, Frederick Ramm, Chris MacNally, and many others. A special thanks to Colin Reilly from New York City NYCDoITT who has helped on many occasions fully understand the source data and find the best decision translating it to OpenStreetMap.