Montgomery County, just north of Houston, has added nearly 68,800 housing units since 2020 and grown by roughly 24.9 percent — even as federal hazard data marks it as one of the riskiest places in the country to build a home. It now ranks No. 2 among the nation’s fastest-growing counties with elevated natural disaster risk, trailing only Brunswick County, North Carolina, which grew 26.5 percent over the same span southwest of Wilmington.
The ranking comes from a RealtyHomes analysis that layered Census population and housing estimates against FEMA’s National Risk Index, limiting its scope to U.S. counties with at least 100,000 residents as of July 1, 2025, and FEMA risk ratings of relatively high or very high, according to chron.com. The outlet, in reporting by Molly Wilhelm, found that three Texas counties — Montgomery, Fort Bend, and Collin — placed among the top 10 fastest-growing counties nationally despite carrying elevated disaster designations. Fort Bend County, southwest of Houston, ranked No. 9 after growing approximately 17.4 percent since 2020, while Collin County, north of Dallas, ranked No. 5 with growth of about 20.6 percent. Denton County, in the northern Dallas-Fort Worth metro area, placed No. 11 with an estimated 16.9 percent growth rate and still made the broader top 25 list.
Collin County’s Scale Stands Out
Collin County added more than 221,000 residents between 2020 and 2025, pushing its total population to nearly 1.3 million — a scale of growth RealtyHomes described as standing out even among the other fast-growing counties on its list. Some of that expansion includes separate developments: a planned 740-acre luxury hideaway in north Denton and an 80-year-old Denton ranch, identified as Harris Ranch, slated to become a 53-acre business park, chron.com reported, drawing on the same analysis.
Separate federal hazard data underscores why these counties draw scrutiny. FEMA NRI v1.20 figures compiled by RiskByCounty in March rank Harris County as the single riskiest of Texas’s 254 counties, with a composite hazard score of 99.9 out of 100. Collin County ranks sixth statewide at 98.9, Fort Bend eighth at 97.5, and Denton tenth at 96.9; Montgomery County ranks 14th — meaning three of the four Texas suburban counties flagged in the growth rankings sit among the state’s ten highest hazard-risk jurisdictions.
Flood Risk Reshaped by New Federal Modeling
Version 1.20 of FEMA’s National Risk Index was released in December 2025. In June, FEMA separately released preliminary updated Flood Insurance Rate Maps for Denton County, adjusting flood risk boundaries and Special Flood Hazard Area designations across the fast-growing northern suburb…