St. Louis County 2026 assessment summary reports record over $337 million in new construction in county

St. Louis County’s property tax base grew by more than $337 million in net new construction in the last year, which is an all-time high in the county.

The total countywide increase in market value, including net new construction, is $1,889,075,200. This brings the total assessed estimated market value of all St. Louis County’s properties for 2026 to $30,263,111,700, a more than 6.6% increase from 2025.

These are among the details released in the 2026 St. Louis County assessment summary. The assessment summary highlights key valuation information compiled through a mass appraisal process, involving the analysis of all “open market” sales that occurred between Oct. 1, 2024, and Sept. 30, 2025.