Social Vulnerability Index
How many people is socially vulnerable to hazards and disasters?
The Social Vulnerability Index (SVI) measures how resilient communities are to external stresses like natural disasters, economic shifts, or health crises. It incorporates factors such as income, housing, disability, and access to transportation.
When SVI is high, it suggests that residents may face more difficulty recovering from disruptions due to limited resources or structural barriers. Neighborhoods with high SVI often experience slower recoveries and greater health or safety risks. Cities can respond by directing investments and emergency planning efforts to areas with higher vulnerability.
When SVI is low, it reflects a community with strong support systems and the capacity to respond to and recover from crises effectively.
Primary Indicator
Percentage of city residents living in a high-vulnerability census tract
Data by census tract were obtained from the CDC/ATSDR. The Social Vulnerability Index (SVI) is calculated by ranking 16 social factors across four domains for U.S. census tracts with non-zero populations. These rankings are combined into domain-specific percentiles, which are then aggregated to determine each tract's overall SVI value. The SVI ranges from 0 to 1, where 0 represents the least, and 1 is the most socially vulnerable in the US. With these SVI values, we then calculated the percentage of city residents living in high-vulnerability census tracts following these steps:
- First, we obtained the list of census tracts with an SVI of .7501, as defined by the CDC/ATSDR or above, to determine the percentage of city residents residing in such high-vulnerability tracts. We excluded census tracts in Puerto Rico from this calculation because they are not included in the U.S.-wide ranking.
- Next, we summed the total population of these tracts.
- Finally, we divided this total population by the city's overall population for each available year.
For more information on the methodology and calculations of the SVI, please visit the source's site here.
Additional Indicators
Average social vulnerability index by city
Data by census tract were obtained from the CDC/ATSDR. We obtained the average SVI values for all census tracts within the city weighted by the total population of each census tract. We excluded census tracts in Puerto Rico from this calculation because they are not included in the U.S.-wide ranking.
For more information on the methodology and calculations, please visit the source's site here.
Percentage of city residents by social vulnerability level
Data by census tract were obtained from the CDC/ATSDR. Then, to calculate the percentage of residents categorized by level of social vulnerability, we followed this process:
- First, we classified the vulnerability level of each census tract based on its SVI value, utilizing the four predefined categories established by the CDC/ATSDR. These categories are: low vulnerability for tracts scoring between 0 and 0.25, low-medium vulnerability for scores ranging from 0.2501 to 0.5, medium-high vulnerability for scores between 0.5001 and 0.75, and high vulnerability for scores falling within the range of 0.7501 to 1. We excluded census tracts in Puerto Rico from this calculation because they are not included in the U.S.-wide ranking.
- Then, we aggregated the total population of census tracts falling within each vulnerability category.
- Finally, we divided this sum by the total population of the city to derive the respective percentages.
For more information on the methodology and calculations of the SVI, please visit the source's site here.