78663 ZIP Code, Round Mountain, TX
78663 is a ZIP code in Round Mountain, Texas — mostly in Blanco County (93% of its land), with smaller parts in Travis and Hays counties. It covers 108 square miles of land. The closest ZIP codes are 78657, 78636 and 78669. 503 people live here in 276 households, fewer than in most Texas ZIP codes. It is rural, with fewer than 100 people per square mile, and most homes are owner-occupied (83%). Median household income is $168,125, well above the Texas median of $78,476; the median age is 65.4, older than most ZIP codes.
Quick facts
- Mailing city: Round Mountain, TX
- County: Blanco County
- Land area: 108 sq mi
- Population: 503
- Median household income: $168,125
- Carrier routes: 1 (443 homes)
Key figures
| Measure | Value |
|---|---|
| Residents | 503 |
| Households | 276 |
| Median household income | $168,125 |
| Income per person | $100,059 |
| Median age | 65.4 |
| Homeowners | 83.0% |
| Median home value | $356,800 |
| Median rent | $1,688 |
| Bachelor's degree or higher | 42.7% |
| Average commute (minutes) | 50.5 |
| Households with kids under 18 | 7.2% |
| Moved in the past year | 3.8% |
| Below the poverty line | 3.6% |
| Broadband internet | 94.2% |
| Speak a non-English language at home | 8.9% |
Household income
| % of households | Value |
|---|---|
| <$10K | 6.5% |
| $10–15K | 0.0% |
| $15–25K | 0.7% |
| $25–35K | 0.0% |
| $35–50K | 7.6% |
| $50–75K | 15.9% |
| $75–100K | 12.0% |
| $100–150K | 6.2% |
| $150–200K | 21.4% |
| $200K+ | 29.7% |
Age
| % of all residents | Value |
|---|---|
| <10 | 1.0% |
| 10–19 | 4.0% |
| 20–24 | 0.0% |
| 25–34 | 0.2% |
| 35–44 | 9.3% |
| 45–54 | 10.7% |
| 55–64 | 23.7% |
| 65–74 | 34.6% |
| 75+ | 16.5% |
Tenure
| % of housing units | Value |
|---|---|
| Owned, with mortgage | 49.3% |
| Owned outright | 31.0% |
| Rented | 15.7% |
| Vacant | 4.0% |
Type of building
| % of housing units | Value |
|---|---|
| Detached house | 93.1% |
| Townhome | 0.0% |
| 2–4 units | 0.0% |
| 5–19 units | 0.0% |
| 20+ units | 0.0% |
| Mobile / other | 6.9% |
Businesses in 78663
32 business establishments with 134 employees (ZIP Codes Business Patterns 2023).
- Construction: 9
- Professional, Scientific, and Technical Services: 5
- Retail Trade: 4
- Manufacturing: 3
- Wholesale Trade: 3
- Finance and Insurance: 3
EDDM carrier routes
78663 has 1 USPS carrier routes with 443 residential and 19 business mailboxes. Open the EDDM route map.
Carrier routes in 78663
78663 has 1 USPS carrier routes (1 highway contract (H)) with 443 residential and 19 business mailboxes. Routes range from 443 homes (H001) to 443 homes (H001); the median route has 443 homes. The Census counted 276 households in 78663 (2020–2024 average); USPS counts current mailboxes, including new and vacant homes.
| Homes per route | Routes |
|---|---|
| 1–249 | 0 |
| 250–499 | 1 |
| 500–749 | 0 |
| 750–999 | 0 |
| 1,000–1,499 | 0 |
| 1,500+ | 0 |
Every carrier route in 78663
| Route | Type | Homes | Businesses | Est. median income | Est. owners | Est. families with kids | Est. moved in past year |
|---|---|---|---|---|---|---|---|
| H001 | Highway contract | 443 | 19 | $111,092 | 86.5% | 13.9% | — |
Income, owners, families and movers are estimates for each route (how we estimate them); mailbox counts are current USPS figures. Open 78663 on the EDDM route map.
How route demographics are estimated
Mailbox counts come from USPS; demographics are estimates
The number of homes and businesses on each carrier route is the current USPS EDDM count. The Census Bureau does not publish figures for carrier routes, so income, homeownership, ages, families, movers and housing age on a route are EDDM2GO estimates built from Census block groups (neighborhood areas of roughly 600 to 3,000 people).
How a route gets its figures: the block-group length-share method
We trace each route's streets every 25 meters and record which block group each stretch falls in. The route's homes are spread along its streets in proportion to length, so a route with 60% of its street length in one block group is assumed to have 60% of its homes there. Each block group then contributes its Census counts in proportion to the share of its housing units that sit on the route (capped at the whole block group). Medians are recalculated from the combined income, home-value and age brackets, the way the Census Bureau computes them, not averaged.
Margins of error
Census survey figures carry a margin of error at 90% confidence; we carry it through the calculation and show it as ±. Our margins treat the route-to-block-group split as exact, so the real uncertainty is larger. Routes with fewer than 100 estimated households, large margins, or streets we could not place are flagged.
Different years
USPS mailbox counts are current. Census figures are 5-year averages for 2020–2024, so a new subdivision may have more homes on the route today than the Census counted. Use the route figures to compare routes with each other, not as an exact head count.
Why some routes show identical figures
Two routes that run through the same block group get the same percentages and medians, because the Census publishes one set of figures for the whole block group. Their mailbox counts still differ, and those are exact.
Route and mailbox counts: USPS EDDM route data. Route demographics: EDDM2GO estimates from U.S. Census Bureau American Community Survey 5-year block-group data (2020–2024) and 2024 cartographic block-group boundaries. This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.
Nearby ZIP codes
- 78657 — Horseshoe Bay city, TX (9.1 mi)
- 78636 — Johnson City city, TX (9.6 mi)
- 78669 — Briarcliff village, TX (11.4 mi)
- 78654 — Marble Falls city, TX (12.4 mi)
- 78620 — Dripping Springs city, TX (16.8 mi)
- 78639 — Kingsland CDP, TX (18.7 mi)
- 78635 (20.1 mi)
- 78645 — Lago Vista city, TX (20.4 mi)
Areas that include 78663
- Round Mountain, TX ZIP codes — 1 ZIP code
- Blanco County ZIP codes — 5 ZIP codes
- Texas ZIP code data
Mail every home in 78663
Route counts on this page price as Full Service 6.5 × 9 postcards: we print, bundle by carrier route and hand the mailing to USPS. Prefer to take it to the Post Office yourself? Print only costs less and you pay postage at drop-off.
EDDM guides
ZIP code statistics describe the Census ZIP Code Tabulation Area (ZCTA) 78663, which approximates the USPS ZIP code area. Census figures: American Community Survey 5-year estimates, 2020–2024.
Frequently asked questions
- What city is 78663 in?
- 78663 is a Round Mountain, TX mailing address. By land area, 2% lies inside Round Mountain; the rest is outside any Census-defined city or community.
- What county is 78663 in?
- 78663 is mostly in Blanco County (93% of its land), with smaller parts in Travis and Hays counties.
- What is the population of 78663?
- About 503 people (±157), according to the Census Bureau's American Community Survey 5-year estimates for 2020–2024. The 2020 Census counted 815.
- What is the median household income in 78663?
- $168,125 (±$143,471), compared with $78,476 for Texas as a whole. Half the households in the ZIP code earn more and half earn less.
- How many carrier routes and mailboxes are in 78663?
- 1 USPS carrier routes with 443 residential and 19 business mailboxes (462 in all), from the route data stored by EDDM2GO. An EDDM mailing can target any combination of these routes.
- What ZIP codes are near 78663?
- The closest, measured center to center: 78657 (9.1 mi, Horseshoe Bay), 78636 (9.6 mi, Johnson City), 78669 (11.4 mi, Briarcliff), 78654 (12.4 mi, Marble Falls), 78620 (16.8 mi, Dripping Springs) and 78639 (18.7 mi, Kingsland).
This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.