ZIP 21771

21771 is one of 28 ZIP codes that lie mostly in Frederick County, MD — 51% of its own area is in the county.

Shaded by typical home value, it ranks 5 of the 23 with a value.

4 school locations in 21771: 3 elementary, 1 middle.

In alphabetical order: Mount Airy Elementary, Mount Airy Middle, Parr's Ridge Elementary, Twin Ridge Elementary. Locations only — no ratings are shown here.

In January 2000 the typical home in 21771 was worth $207,953.

Values peaked at $633,941 in July 2026. The latest reading is the peak.

As of August 2026: $633,818, +0.9% over twelve months.

Start with the typical home: $633,818. Put 20% down and borrow $507,054 at 7.40%, the 30-year fixed average as of October 8, 2026.

That is $3,511 a month in principal and interest.

The median household here earns $154,844 a year, $12,904 a month. So the payment takes 27.2% of income — rated “affordable” (Lotvox ZIP bands: under 28% affordable · 28–36% stretched · 36%+ severe).

The line holds today's rate fixed and moves only the price: at that rate, the same share was 8.9% in 2000.

Take the typical home's price each month, borrow 80% at that month's actual 30-year average rate: in January 2000 (8.21%) the payment was $1,245.

In December 2020, with rates at 2.68%, it was $1,566.

By August 2026, at 6.67%, it was $3,261 — +108% since December 2020, while the home's value moved +31%.

Reported values rose +205% since January 2000.

General prices (CPI-U) rose +97% over the same span.

Divide one by the other: in August 2026 dollars, the 2000 home was worth $410,417. So the real change is +54%, not +205%.

21771: +205% since January 2000.

Frederick County: +189% since January 2000.

Maryland: +180% since January 2000 — 21771 ran ahead of it by 24 points.

Owning the typical home costs about $4,145 a month once taxes and insurance (estimated at 1.2% of price a year) are added. Renting runs about $2,563 a month.

Price divided by a year's rent: 20.6. Lotvox reads under 15 as favoring buying and 20 or more as favoring renting.

Picture the Listings Flow Ladder as a basin: new listings pour in from the faucet, the homes for sale are the water, and closed sales run out the drain. Coming in — new listings: about 35 a month (Redfin, 3-month rolling data through August 2026). That is 68% of the 2015–2019 level for the same months.

On the shelf — homes for sale at the end of the period: 69.

Going out — closed sales: about 32 a month. That is 65% of the 2015–2019 level for the same months.

The ladder: homes for sale ÷ monthly sales = 2.2 months of supply — below the 4–6 month range Lotvox treats as balanced. In the basin, that is the water level against the shaded balanced band.

The net reading: about 3 more homes came on than sold each month, so inventory is growing. The basin is filling.

Homes sold: about 32 a month in August 2026 (Redfin).

The 2015–2019 level for the same month was 36 — so sales ran at 89% of it, and below it in 19 of the last 24 months.

Across Frederick County, builders pulled permits for 1,168 new homes in 2025.

Of those, 70% were in 1-unit buildings (the Census Bureau's category for detached and attached single homes).

This ZIP sits in Frederick County. IRS tax returns for 2022-2023: among the ten counties sending the most households, 5,021 moved in. Among the ten receiving the most, 3,461 moved out.

Net across those counties: +1,560 households. Beside it, homes for sale in this ZIP: 69 in June 2026.

Most arrivals came from Montgomery, MD (2,352 households); most departures went to Washington, MD (953).