Published October 4, 2026 in Market Update

One part of Herndon is much tighter than the other

By Elizabeth Sachero-Perez

Real estate, Herndon

Thinking about buying or selling in Herndon? The ZIP code matters more than most people realize. The Real Estate Data Aggregator counted 304 homes sold across Herndon in the three months ending July 31, 2026. That is up 9% from the same months in 2025. But that combined number hides a real split between 20170 and 20171.

The supply gap is the story

Supply is the fastest way to see how different these two ZIP codes are. The Real Estate Data Aggregator put months of supply in 20170 at 1.2 months. That is down 0.7 months from a year before. In 20171, the Real Estate Data Aggregator counted 2.2 months of supply, up 0.3 months from the year before. Both numbers are still low. But 1.2 months is noticeably tighter than 2.2 months, and they are moving in opposite directions.

Realtor.com reported that active listings grew 5.5% nationwide, topping 1.16 million homes for sale. Herndon's 20171 is closer to that national trend, with inventory up 24.7% year over year. ZIP 20170 went the other way: homes for sale fell 32.1% from a year before, according to the Real Estate Data Aggregator.

Prices and speed, side by side

The median sale price in 20171 was $850,000, up 14.9% from a year before, according to the Real Estate Data Aggregator. That is a large move in one year. In 20170, the median was $713,270, up a much smaller 0.9%. Both ZIPs are selling above list price on average, but 20170 is moving faster to contract. The Real Estate Data Aggregator found that 57.5% of homes in 20170 went under contract within two weeks of listing, up 5.7 points from 2025. In 20171, that share was 50%, down 5 points.

Rates are adding pressure everywhere

Mortgage rates are not helping buyers in either ZIP. CNBC reported the average contract rate for a 30-year fixed mortgage with a conforming loan balance at 7.30% as of September 30, 2026. Realtor.com reported rates surged above 7% for the first time since January 2025. The Federal Housing Finance Agency said U.S. house prices rose 2.6% from July 2025 to July 2026. Herndon's 20171 outpaced that national figure by a wide margin.

What this means for you

If your home is in 20170, you are in a tighter market. Inventory is down sharply, and more than half of homes are going under contract within two weeks. If your home is in 20171, there is more competition from other sellers, prices are rising quickly, and buyers have a little more time to decide. Neither ZIP is slow. But the right pricing and timing strategy looks different depending on which side of town you are on.

Realtor.com also noted that 20.8% of listings nationally took a price cut in September, the highest share since October 2022. In Herndon's tighter ZIP, that risk is lower. In the ZIP with more inventory, pricing carefully from the start matters more.