About This Map

This bivariate map shows the intersection of evacuation route availability and wildfire burn hazard for approximately 30,728 U.S. Census Designated Places (CDPs). Each dot represents a single community.

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Exit Classification

Exits are the number of roads that cross the boundary of a community’s perimeter, representing potential evacuation routes. Road networks are sourced from OpenStreetMap via the OSMnx Python package.

• Low: 6 or fewer boundary-crossing roads
• High: More than 6 boundary-crossing roads

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Burn Classification

Burn hazard is computed as a composite score combining:

1. Mean burn probability within the community perimeter (min-max normalized)
2. Maximum burn probability within the community perimeter (min-max normalized)

These two normalized values are averaged to produce a single burn hazard score (0–1) for each community. The score is then classified using percentile-based cutoffs computed from the full national dataset:

• Low: Below the 50th percentile (score ≤ 0.0027)
• Medium: 50th to 90th percentile (0.0027 < score ≤ 0.0352)
• High: Above the 90th percentile (score > 0.0352)

Burn probability rasters are from the USFS Wildfire Risk to Communities dataset (270 m resolution). Zonal statistics (mean, max) are calculated within each CDP polygon boundary.

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How to Read the Colors

The map uses a 2×3 bivariate color grid. Each community is colored by its combination of exit classification (rows) and burn classification (columns):

	Burn Classification →
Exits ↓	Low	Medium	High
Low
High

• ■ Dark magenta = Highest risk (few exits + high burn hazard)
• ■ Red = High burn but adequate exits
• ■ Light = Lowest risk (many exits + low burn hazard)

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Data Sources

Place Boundaries	U.S. Census Bureau TIGER/Line Shapefiles (2023)
Demographics	U.S. Census ACS 5-Year Estimates (2021)
Road Networks	OpenStreetMap via OSMnx
Burn Probability	USFS Wildfire Risk to Communities (RDS-2020-0016-2), 270 m resolution
WUI Classification	SILVIS Lab, University of Wisconsin-Madison