U.S. housing starts were estimated at a seasonally adjusted annual rate of 1.221 million in September, the Census Bureau and Department of Housing and Urban Development reported October 20. That was 5.2% below the revised August estimate of 1.288 million.

The uncertainty matters. The reported monthly change carries a margin of plus or minus 11.8 percentage points at the 90% confidence level. Because that interval includes zero, the release does not establish a statistically significant decline. A single monthly estimate should not be treated as proof of a sustained construction downturn.

Building permits ran at a 1.400 million annual rate, 0.2% below August. Single-family authorizations were at an 845,000 rate, down 4.0%. Permits describe authorization to build, while starts measure projects getting underway; neither is a count of completed homes.

Completions were estimated at a 1.192 million annual rate. These annualized figures express the pace of activity after seasonal adjustment, not the number of homes built during September alone. The agencies caution that construction estimates are subject to revision and that identifying an underlying trend takes multiple months.