‘Built to burn.’ L.A. let hillside homes multiply without learning from past mistakes

People continued to move into fire-prone foothills and valleys. Between 1990 and 2020, the number of homes in the metro Los Angeles region’s wildland-urban interface, where human development meets undeveloped wildland, swelled from 1.4 million to 2 million — a growth rate of 44%, according to David Helmers, a geospatial data scientist in the Silvis Lab at the University of Wisconsin-Madison.