Title page 1

Contents 1

Abstract 2

1. Introduction 3

2. Measuring Flood Risk 6

3. Data 8

4. Facts About the Distribution of Flood Risk 11

4.1. Trends in Exposure 11

4.2. Who Is Exposed to Flood Risk? 13

4.3. Housing Wealth and Flood Risk Exposure 16

5. Insurance and Adaptation to Flood Risk 18

6. Discussion 21

References 24

Appendix A. Appendix Figures 53

Table 1. Balance Table of Demographics and Housing by Floodplain Status (EIF Data) 50

Table 2. Balance Table of Demographics and Housing by Floodplain Status (ACS Data) 51

Table 3. Household Characteristics by Floodplain and Adapted Status 52

Table 4. A typology of flood-risk-exposed households across vulnerability dimensions 52

Figure 1. Example of Different Floodplain Exposure Definitions 27

Figure 2. Population Level and Share Living in Floodplains in the US, 1999-2023 28

Figure 3. Migration Flows To and From Floodplains, Block vs. Parcel Exposure 29

Figure 4. Trends in the Share of the Population in Floodplains by Income, 1999-2023 30

Figure 5. Trends in the Share of the Population in Floodplains by Household Tenure, 1999-2023 31

Figure 6. Trends in the Share of the Population in Floodplains by Income Percentile: 2013 vs. 2023 32

Figure 7. Trends in the Share of the Population in Floodplains by Income Percentile & Tenure: 2013 vs. 2023 33

Figure 8. Trends in the Share of the Population in Floodplains by Income Percentile, Tenure, and Housing Type: 2013 vs. 2023 34

Figure 9. Trends in the Share of the Population in Floodplains by Age, Tenure, and Race/Ethnicity: 2013 vs. 2023 35

Figure 10. Trends in the Population in Floodplains by Income Percentile, Tenure, and Housing Type 36

Figure 11. Trends in the Population in Floodplains by Income Percentile, Tenure, and Race/Ethnicity 37

Figure 12. Share of the Population in Floodplains by Income Percentile, Tenure, and Housing Type, Split by Coastal vs. Non-coastal Counties 38

Figure 13. Trends in the Share of the Population in Floodplains using Aggregate Data 39

Figure 14. Trends in the Share of the Population in Floodplains by Home Value Percentile and Race/Ethnicity: 2013 vs. 2023 40

Figure 15. Trends in the Share of the Population in Floodplains by Income Percentile and Exposure Type 41

Figure 16. Trends in the Share of Total Housing Value Owned by Income Percentile and Floodplain Status 42

Figure 17. Uninsured Rates by Floodplain Status, 2005-2023 43

Figure 18. Average Household Income by Insurance & Floodplain Status, 2005-2023 43

Figure 19. Uninsured Rates by Race/Ethnicity & Floodplain Status, 2005-2023 44

Figure 20. Insurance Payment by Floodplain Status, 2005-2023 44

Figure 21. Insurance Payment as a Share of Household Income, 2005-2023 45

Figure 22. Insurance Payment as a Share of Household Income by Income Vigintiles & Floodplain Status, 2005-2023 46

Figure 23. Uninsured Rate by Income Vigintiles & Floodplain Status, 2005-2023 47

Figure 24. Average Flood Losses to Income Ratio by Income Percentile, Insurance Status, & Floodplain Status (Single-Family Buildings) 48

Figure 25. Proportion of Households in Levee-protected Areas, by Income 49

Figure A1. Trends in the Share of the Population in Floodplains by Income Percentile, Tenure, and Race/Ethnicity: 2013 vs. 2023 53

Figure A2. Average Annual Expected Flood Damages and Insurance Payments by Income Percentile and Floodplain & Insurance Status 54