ZIP 78640 vs ZIP 78666

78640 is one of 7 ZIP codes that lie mostly in Hays County, TX — 84% of its own area is in the county.

Shaded by typical home value, it ranks 7 of the 7 with a value.

15 school locations in 78640: 9 elementary, 4 middle, 2 high.

In alphabetical order: ARMANDO CHAPA MIDDLE, CAMINO REAL EL, D J RED SIMON MIDDLE, HEMPHILL EL, and more on the ZIP page. Locations only — no ratings are shown here.

78666 is one of 7 ZIP codes that lie mostly in Hays County, TX — 78% of its own area is in the county.

Shaded by typical home value, it ranks 6 of the 7 with a value.

15 school locations in 78666: 9 elementary, 3 middle, 3 high.

In alphabetical order: BLANCO VISTA EL, BONHAM PRE-K SCHOOL, BOWIE EL, CROCKETT EL, and more on the ZIP page. Locations only — no ratings are shown here.

In January 2007 the typical home in 78640 was worth $160,710.

Values peaked at $421,969 in July 2022. The latest reading is −30.5% from that peak.

As of August 2026: $293,386, −6.6% over twelve months.

Start with the typical home: $293,386. Put 20% down and borrow $234,709 at 7.40%, the 30-year fixed average as of October 8, 2026.

That is $1,625 a month in principal and interest.

The median household here earns $88,533 a year, $7,378 a month. So the payment takes 22.0% 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 12.1% in 2007.

Take the typical home's price each month, borrow 80% at that month's actual 30-year average rate: in January 2007 (6.22%) the payment was $789.

In December 2020, with rates at 2.68%, it was $847.

By August 2026, at 6.67%, it was $1,509 — +78% since December 2020, while the home's value moved +12%.

Reported values rose +83% since January 2007.

General prices (CPI-U) rose +64% over the same span.

Divide one by the other: in August 2026 dollars, the 2007 home was worth $263,955. So the real change is +11%, not +83%.

78640: +83% since January 2007.

Hays County: +86% since January 2007.

Texas: +106% since January 2007 — 78640 ran behind it by 24 points.

Against 1,763 Texas ZIP codes, 78640 sits at the 61st percentile for affordability (price vs local income).

4th for appreciation (recent value growth); 63rd for rental yield (rent vs price).

Owning the typical home costs about $1,918 a month once taxes and insurance (estimated at 1.2% of price a year) are added. Renting runs about $1,566 a month.

Price divided by a year's rent: 15.6. Lotvox reads under 15 as favoring buying and 20 or more as favoring renting.

In January 2007 the typical home in 78666 was worth $165,917.

Values peaked at $395,916 in July 2022. The latest reading is −21.3% from that peak.

As of August 2026: $311,558, −3.3% over twelve months.

Start with the typical home: $311,558. Put 20% down and borrow $249,246 at 7.40%, the 30-year fixed average as of October 8, 2026.

That is $1,726 a month in principal and interest.

The median household here earns $55,478 a year, $4,623 a month. So the payment takes 37.3% of income — rated “severe” (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 19.9% in 2007.

Take the typical home's price each month, borrow 80% at that month's actual 30-year average rate: in January 2007 (6.22%) the payment was $815.

In December 2020, with rates at 2.68%, it was $886.

By August 2026, at 6.67%, it was $1,603 — +81% since December 2020, while the home's value moved +14%.

Reported values rose +88% since January 2007.

General prices (CPI-U) rose +64% over the same span.

Divide one by the other: in August 2026 dollars, the 2007 home was worth $272,507. So the real change is +14%, not +88%.

78666: +88% since January 2007.

Hays County: +86% since January 2007.

Texas: +106% since January 2007 — 78666 ran behind it by 18 points.

Against 1,763 Texas ZIP codes, 78666 sits at the 11th percentile for affordability (price vs local income).

17th for appreciation (recent value growth); 40th for rental yield (rent vs price).

Owning the typical home costs about $2,037 a month once taxes and insurance (estimated at 1.2% of price a year) are added. Renting runs about $1,414 a month.

Price divided by a year's rent: 18.4. 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 156 a month (Redfin, 3-month rolling data through August 2026). That is 133% of the 2015–2019 level for the same months.

On the shelf — homes for sale at the end of the period: 649. That is 277% of the 2015–2019 level for the same months.

Going out — closed sales: about 157 a month. That is 155% of the 2015–2019 level for the same months. The drain is drawn 42% narrower: the share of homes for sale that sell each month is 58% of its 2015–2019 level.

The ladder: homes for sale ÷ monthly sales = 4.1 months of supply — inside the 4–6 month balanced range. In the basin, that is the water level against the shaded balanced band.

The net reading: about 2 more homes sold than came on each month, so inventory is shrinking. The basin is draining.

Homes sold: about 157 a month in August 2026 (Redfin).

The 2015–2019 level for the same month was 90 — so sales ran at 174% of it, and below it in 0 of the last 24 months.

Across Hays County, builders pulled permits for 4,595 new homes in 2025.

Of those, 90% were in 1-unit buildings (the Census Bureau's category for detached and attached single homes).

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 127 a month (Redfin, 3-month rolling data through August 2026). That is 196% of the 2015–2019 level for the same months.

On the shelf — homes for sale at the end of the period: 504. That is 282% of the 2015–2019 level for the same months.

Going out — closed sales: about 78 a month. That is 129% of the 2015–2019 level for the same months. The drain is drawn 54% narrower: the share of homes for sale that sell each month is 46% of its 2015–2019 level.

The ladder: homes for sale ÷ monthly sales = 6.4 months of supply — above the 4–6 month balanced range. In the basin, that is the water level against the shaded balanced band.

The net reading: about 49 more homes came on than sold each month, so inventory is growing. The basin is filling.

Homes sold: about 78 a month in August 2026 (Redfin).

The 2015–2019 level for the same month was 48 — so sales ran at 163% of it, and below it in 0 of the last 24 months.

Across Hays County, builders pulled permits for 4,595 new homes in 2025.

Of those, 90% were in 1-unit buildings (the Census Bureau's category for detached and attached single homes).

This ZIP sits in Hays County. IRS tax returns for 2022-2023: among the ten counties sending the most households, 8,569 moved in. Among the ten receiving the most, 6,381 moved out.

Net across those counties: +2,188 households. Beside it, homes for sale in this ZIP: 649 in June 2026.

Most arrivals came from Travis, TX (5,064 households); most departures went to Travis, TX (2,606).

This ZIP sits in Hays County. IRS tax returns for 2022-2023: among the ten counties sending the most households, 8,569 moved in. Among the ten receiving the most, 6,381 moved out.

Net across those counties: +2,188 households. Beside it, homes for sale in this ZIP: 504 in June 2026.

Most arrivals came from Travis, TX (5,064 households); most departures went to Travis, TX (2,606).

County assessor records list 73 properties with a market value here. Their average assessed market value is $323,706; the typical home value is $311,558.

The assessor average sits +3.9% from the market figure — an average against a typical value, so treat it as a check, not a verdict.