Explore The underground border at street level

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How to use the map

• Use the time slider to see street network changes across four periods: pre-1975, 1976–1990, 1991–2005, 2006–2020.
• Toggle between the globe view and map view using the icons in the top right.
• Click on a city to see its SNDi value.
• Darker colors indicate more disconnected (more sprawly) street networks.