S. 3875 would codify the National Risk Index (NRI), a tool used to assess the vulnerability of communities to natural hazards, and the bill would require the Federal Emergency Management Agency (FEMA) to improve, update, and integrate the NRI into federal disaster relief programs. The bill would require FEMA to use NRI data to identify census tracts with the highest vulnerability ratings for natural disasters and designate those areas as community disaster resilience zones. In addition, for projects located within those zones, S. 3875 would authorize FEMA to use the Disaster Relief Fund (DRF) to increase the share the federal government covers for grants under the Building Resilient Infrastructure and Communities (BRIC) program. The bill would allow the federal contribution to rise from the current 75 percent to 90 percent; state, local, and tribal governments would continue to fund the remainder of the grants.