Gaithersburg, MD

ZIP code 20899 is assigned to Gaithersburg, MD, and falls within Montgomery County. Like every US postal code, it began as a mail-routing device rather than a geographic boundary — the US Postal Service groups delivery routes under a single code so carriers and sorting equipment can process mail efficiently. Today it also serves as a practical shorthand for the area itself: roughly 106 people live inside it.

At 1,000 residents per square mile spread over 0.106 square miles, 20899 reads as a suburban area. It is a sparsely populated postal code, and density shapes almost everything else on this page — how people get to work, whether they own or rent, and what housing costs.

Household earnings are well below the national median. At $23,917, 20899 ranks among the lower-income postal codes, ahead of 1% of them. The US median for comparison is $70,109. Bear in mind that median income describes the midpoint household, not the average — it is not pulled upward by a handful of very high earners the way a mean would be.

The building stock is dominated by larger apartment buildings of twenty units or more, which account for 84.3% of housing units here. The median construction year is 1985, making the housing here from the later twentieth century. At 0.0%, vacancy is low — housing here is tightly held.

The population skews considerably older than the national median, with a median age of 70.4 against 42 nationally. Households average just 1.19 people, and 83.1% consist of one person living alone — a signature of areas with a lot of studio and one-bedroom stock.

Getting to work takes 37.0 minutes on average one way. The dominant mode is public transit at 100.0% of workers, while 100.0% take public transit. Commute patterns are one of the better proxies for how a place actually functions day to day.

Beyond addressing mail, 20899 does a lot of quiet administrative work. Retailers use it to calculate shipping and sales tax at checkout. Insurers use it to set premiums, since risk profiles vary geographically. Employers and marketers use it to define service areas. Government agencies use it to route benefits and organise reporting. If you have ever been asked for a postal code by a form that clearly does not intend to send you anything, this is why.

For anyone weighing a move, 20899 offers a compact profile of Gaithersburg: 106 residents, a median household income of $23,917, 33.0% of adults holding a bachelor's degree or higher, and an unemployment rate of 56.2%. A handful of figures like these answer more relocation questions than most neighbourhood guides do.

One caution worth repeating: a postal code is not a neighbourhood. 20899 may cover parts of several distinct areas, and a single neighbourhood in Gaithersburg may be split across more than one code. Boundaries also shift as USPS adjusts delivery routes. Treat the figures here as describing a delivery area, which is what they actually measure.