The median lot size for new single-family detached homes that were sold in 2019 dropped to a record-low 8,177 square feet (0.188 of an acre), down 390 square feet since 2018, according to the latest figures from the Census Bureau.

The shrinking median lot size largely reflects the shift in speculatively built (or spec) home building toward smaller lots. A decade ago, 27% of all sold single-family detached homes were sitting on lots under 0.16 acres and 21% were occupying lots between 0.16 and 0.25 acres.

Fast forward to 2019, these shares increased to 37% and 24%, respectively. At the other end of the lot size distribution, the share of spec homes built on larger lots exceeding half an acre shrunk from 15% in 2009 to 10% in 2019.

Regional Size Differences

While the nation’s production of spec homes shifts toward smaller lots, the regional differences in lot sizes persist. Looking at single-family detached spec homes started in 2019, the median lot size in New England is three times as large as the national median.

New England is known for strict local zoning regulations that often require very low densities. Therefore, it is not surprising that single-family detached spec homes started in New England are built on some of the largest lots in the nation, with more than half of the lots exceeding half an acre. The neighboring Mid-Atlantic and more distant East South Central divisions are next on the list with the median lot occupying about a third of an acre (0.3 acres).

In the South, the West South Central division stands out for starting half of single-family detached spec homes on lots under 0.16 acres. This is significantly lower than the median lot sizes in the neighboring East South Central division where half of the lots exceed 0.3 acres.

The Pacific division — where densities are high and developed land is scarce — has the smallest lots, with half of the lots being under 0.15 acres. The bordering Mountain division also reports typical lots smaller than a national median, 0.17 acres.

NAHB economist Natalie Siniavskaia provides more analysis in this Eye on Housing blog post.