78666 ZIP Code — San Marcos, TX
Hays County, Texas
ZIP code 78666 is located in San Marcos, Texas, within Hays County. It covers approximately 192.39 square miles and serves a population of 86,530 residents. This is a standard ZIP code in the Central (CT) timezone, served by area code 512/737.
About ZIP code 78666
The housing stock consists of a significant share of large multi-unit buildings. Much of the housing stock is relatively new, reflecting recent development activity. Median home value is $248,700. Renters make up the majority at 63%, typical of denser urban areas.
Median household income is $52,432. Poverty affects 24% of residents, above the national average.
The dominant occupation class is management, business, and professional, with education and healthcare as the leading industry. The average commute of 25 minutes is near the national average.
Educational attainment is near the national average, with 33% of residents holding a bachelor's degree or higher.
17% of residents lack health insurance, above the national average.
86,530
population
192.39
sq mi land
Standard
ZIP type
Central (CT)
timezone
78666 ZIP code map
Cities in ZIP code 78666
Below are the cities the US Postal Service accepts for ZIP code 78666. Using any city not on this list may result in mail delivery delays.
| City | Status |
|---|---|
| San Marcos | Preferred |
Nearby ZIP codes
78656 Maxwell (12.1 mi)
78132 New Braunfels (12.5 mi)
78676 Wimberley (12.7 mi)
78130 New Braunfels (12.7 mi)
78133 Canyon Lake (13.1 mi)
78640 Kyle (13.1 mi)
78135 New Braunfels (13.6 mi)
78655 Martindale (13.9 mi)
78623 Fischer (14.5 mi)
78619 Driftwood (16 mi)
78610 Buda (17.1 mi)
78123 Mc Queeney (19.2 mi)
Demographics
updated 06/2026
| Population | |
|---|---|
| Total population | 86,530 |
| Population density | 450 / sq mi |
| State FIPS | 48 |
| County FIPS | 209 |
| Geography | |
|---|---|
| Land area | 192.39 sq mi |
| Water area | 1.02 sq mi |
| Latitude | 29.8785 |
| Longitude | -98.0200 |
| Timezone | Central (CT) |
| Area code | 512/737 |
Total population by age
Gender
Race & ethnicity
Economics
updated 06/2026
Household income
| Income range | This ZIP | County avg | State avg |
|---|---|---|---|
| Under $50k | 55.0% | 35.3% | 39.5% |
| $50k – $100k | 29.5% | 31.9% | 30.1% |
| $100k – $200k | 12.4% | 23.5% | 22.6% |
| Over $200k | 3.1% | 9.3% | 7.8% |
Demographics & statistics
86,530
Population
450
People per sq mi
26.5
Median age
$52,432
Median household income
$27,457
Per capita income
$248,700
Median home value
$1,245
Median monthly rent
37.4%
Home ownership
24.4%
Poverty rate
6.4%
Unemployment
15,150
Housing units
33.3%
Bachelor's or higher
Age distribution
Male
Female
1,660
Under 5
1,751
1,476
5–9
1,557
1,788
10–14
1,886
4,487
15–19
4,734
9,906
20–24
10,450
6,763
25–34
7,133
4,568
35–44
4,819
3,398
45–54
3,584
1,572
55–59
1,659
1,900
60–64
2,005
2,904
65–74
3,064
1,146
75–84
1,209
541
85+
570
← Male
Female →
Age summary
| Group | Count | % |
|---|---|---|
| Under 18 | 12,360 | 14.3% |
| 18 and over | 74,170 | 85.7% |
| 65 and over | 9,434 | 10.9% |
| Median age | 26.5 years | |
Race & ethnicity
White
55.8%
Hispanic or Latino
17.6%
Two or more races
14.4%
Other race
5.7%
Black or African American
4.6%
Asian
1.5%
American Indian / Alaska Native
0.3%
Native Hawaiian / Pacific Islander
0.1%
| Group | Count | % |
|---|---|---|
| White | 58,603 | 55.8% |
| Hispanic or Latino | 18,518 | 17.6% |
| Two or more races | 15,154 | 14.4% |
| Other race | 5,976 | 5.7% |
| Black or African American | 4,807 | 4.6% |
| Asian | 1,594 | 1.5% |
| American Indian / Alaska Native | 331 | 0.3% |
| Native Hawaiian / Pacific Islander | 65 | 0.1% |
Household income
| Income range | This ZIP | County avg | State avg |
|---|---|---|---|
| Under $50k | 55.0% | 35.3% | 39.5% |
| $50k – $100k | 29.5% | 31.9% | 30.1% |
| $100k – $200k | 12.4% | 23.5% | 22.6% |
| Over $200k | 3.1% | 9.3% | 7.8% |
Under $10k
9.5%
$10k–$15k
5.2%
$15k–$25k
8.6%
$25k–$35k
11.9%
$35k–$50k
12.7%
$50k–$75k
21.5%
$75k–$100k
11.0%
$100k–$150k
10.4%
$150k–$200k
3.6%
$200k+
5.7%
| Range | % of households |
|---|---|
| Under $10k | 9.5% |
| $10k–$15k | 5.2% |
| $15k–$25k | 8.6% |
| $25k–$35k | 11.9% |
| $35k–$50k | 12.7% |
| $50k–$75k | 21.5% |
| $75k–$100k | 11.0% |
| $100k–$150k | 10.4% |
| $150k–$200k | 3.6% |
| $200k+ | 5.7% |
| Median income | $52,432 |
Housing
Home values
Under $50k
8.7%
$50k–$100k
6.5%
$100k–$150k
9.4%
$150k–$200k
14.1%
$200k–$300k
26.2%
$300k–$500k
27.5%
$500k–$1M
6.7%
$1M+
0.9%
Housing overview
| Metric | Value |
|---|---|
| Median home value | $248,700 |
| Median rent / month | $1,245 |
| Owner occupied | 37.4% |
| Renter occupied | 62.6% |
| Vacant | 7.7% |
| Single-family detached | 38.9% |
| Large apartment buildings | 20.4% |
| Mobile homes | 8.8% |
| Median rooms | 4.7 |
| Avg household size (owned) | 2.61 |
Year built
| Era | % |
|---|---|
| 2020 or later | 1.9% |
| 2010–2019 | 22.9% |
| 2000–2009 | 19.1% |
| 1990–1999 | 16.1% |
| 1980–1989 | 16.1% |
| 1970–1979 | 10.9% |
| 1960–1969 | 4.6% |
| 1950–1959 | 3.7% |
| 1940–1949 | 2.4% |
| 1939 or earlier | 2.3% |
Bedrooms
| Size | % of units |
|---|---|
| No bedroom (studio) | 3.1% |
| 1 bedroom | 14.9% |
| 2 bedrooms | 28.7% |
| 3 bedrooms | 37.8% |
| 4 bedrooms | 14.2% |
| 5+ bedrooms | 1.3% |
Vehicles per household
| Vehicles | % of households |
|---|---|
| No vehicle | 4.9% |
| 1 vehicle | 33.8% |
| 2 vehicles | 39.2% |
| 3 or more | 22.1% |
Heating fuel
| Fuel type | % |
|---|---|
| Utility gas | 20.6% |
| Electricity | 76.3% |
| Propane / LP gas | 2.5% |
| Wood | 0.2% |
| Solar | 0.1% |
| No fuel used | 0.1% |
Households & families
| Household type | Count | % |
|---|---|---|
| Married-couple family | 11,186 | 33.7% |
| Cohabiting couple | 3,275 | 9.9% |
| Male householder, no spouse | 7,736 | 23.3% |
| Female householder, no spouse | 10,976 | 33.1% |
| Households with children under 18 | 6,701 | 20.2% |
| Households with seniors (65+) | 6,190 | 18.7% |
| Average household size | 2.36 | |
Marital status
| Status | Male | Female |
|---|---|---|
| Never married | 56.1% | 52.7% |
| Married | 33.5% | 31.7% |
| Separated | 1.1% | 1.8% |
| Widowed | 1.5% | 5.3% |
| Divorced | 7.8% | 8.4% |
Education
Less than 9th grade
5.2%
Some HS, no diploma
6.4%
HS graduate
25.0%
Some college, no degree
23.5%
Associate's degree
6.5%
Bachelor's degree
20.3%
Graduate / professional
13.0%
| Metric | % |
|---|---|
| HS diploma or higher | 88.3% |
| Bachelor's or higher | 33.3% |
School enrollment (ages 3–17)
| Type | Count | % |
|---|---|---|
| Nursery / preschool | 468 | 1.4% |
| Kindergarten | 721 | 2.1% |
| Elementary school | 4,951 | 14.8% |
| High school | 3,850 | 11.5% |
| College / grad school | 23,566 | 70.2% |
Employment
Industry of employment
Education & healthcare
24.5%
Arts, food & hospitality
15.8%
Retail trade
14.7%
Professional & management
9.8%
Construction
7.1%
Transportation & utilities
6.2%
Manufacturing
5.0%
Other services
4.7%
Finance & real estate
4.1%
Public administration
3.8%
Wholesale trade
2.0%
Information
1.3%
Agriculture & mining
1.0%
Occupation
| Category | % |
|---|---|
| Management, business & arts | 34.4% |
| Service | 22.4% |
| Sales & office | 23.7% |
| Natural resources & construction | 7.8% |
| Production & transportation | 11.6% |
Employment type
| Type | % |
|---|---|
| Private sector | 76.1% |
| Government | 18.4% |
| Self-employed | 5.4% |
| Unpaid family workers | 0.1% |
Commute
| Method | % |
|---|---|
| Drive alone | 73.5% |
| Carpool | 10.5% |
| Public transit | 0.8% |
| Walk | 4.2% |
| Work from home | 8.2% |
| Other means | 2.8% |
| Avg commute (minutes) | 24.6 |
Poverty
All people
24.4%
Under 18 years
24.4%
18 and over
24.5%
Married-couple families
4.3%
Female-led households
30.3%
Income support
| Source | % of households |
|---|---|
| Social Security | 18.1% |
| Retirement income | 15.3% |
| Supplemental Security | 3.1% |
| Cash public assistance | 3.0% |
| Food stamps / SNAP | 8.1% |
Health indicators
| Condition | % |
|---|---|
| Obesity | 30.6% |
| High blood pressure | 23.4% |
| High cholesterol | 25.4% |
| Diabetes | 8.6% |
| Heart disease | 4.3% |
| Stroke | 2.1% |
| Asthma | 10.0% |
| Arthritis | 14.4% |
| Kidney disease | 2.3% |
| Pulmonary disease | 5.0% |
| Cancer | 3.5% |
| Behavior / access | % |
|---|---|
| Smoking | 16.3% |
| Binge drinking | 20.4% |
| No physical activity | 24.5% |
| Less than 7 hrs sleep | 30.8% |
| Depression | 22.9% |
| Fair or poor health | 16.2% |
| Poor mental health | 18.7% |
| Poor physical health | 9.9% |
| No health insurance | 30.3% |
| Visited doctor (checkup) | 66.9% |
| Visited dentist | 53.4% |
| Cholesterol screening | 78.9% |
| Teeth loss | 16.2% |
Veterans & disability
| Veterans | Count | % |
|---|---|---|
| Civilian veterans | 3,401 | 4.6% |
| Disability | % |
|---|---|
| Any disability | 13.8% |
| Under 18 | 7.7% |
| 18–64 years | 11.2% |
| 65 and over | 40.2% |
Health insurance coverage
| Type | % |
|---|---|
| Private insurance | 69.3% |
| Public insurance | 22.8% |
| No insurance | 16.5% |
| Uninsured under 19 | 9.5% |
Language & origin
Language spoken at home (age 5+)
| Language | Count | % |
|---|---|---|
| English only | 83,119 | 96.1% |
| Spanish | 4,425 | 5.3% |
| Other Indo-European | 3,577 | 4.3% |
| Asian & Pacific Islander | 530 | 0.6% |
| Other languages | 252 | 0.3% |
Place of birth & citizenship
| Origin | Count | % |
|---|---|---|
| Native born (US) | 79,422 | 91.8% |
| Born in same state | 78,453 | 90.7% |
| Born in different state | 60,836 | 70.3% |
| Foreign born | 969 | 1.1% |
| Naturalized citizen | 7,108 | 8.2% |
| Not a US citizen | 2,199 | 30.9% |
Ancestry
| Ancestry | Count | % |
|---|---|---|
| Italian | 6,914 | 8% |
| French | 6,410 | 7.4% |
| Arab | 1,726 | 2% |
| Polish | 699 | 0.8% |
| English | 441 | 0.5% |
| Ancestry | Count | % |
|---|---|---|
| German | 249 | 0.3% |
| Norwegian | 58 | 0.1% |
| Irish | 49 | 0.1% |
| Dutch | 24 | 0% |
Technology access
| Metric | % of households |
|---|---|
| Computer access | 38.3% |
| Internet access | 95.8% |
Source: U.S. Census Bureau, American Community Survey 2025 estimates.
Frequently asked questions about ZIP code 78666
What part of San Marcos is ZIP code 78666?
ZIP code 78666 covers a portion of San Marcos, Texas, within Hays County.
What county is ZIP code 78666 in?
ZIP code 78666 falls within Hays County, Texas.
Is ZIP code 78666 mostly rentals?
63% of occupied units in ZIP code 78666 are renter-occupied.
What is the poverty rate in ZIP code 78666?
24% of residents in ZIP code 78666 live below the poverty line, above the national average.
What is the population of ZIP code 78666?
ZIP code 78666 has an estimated population of 86,530 residents, with a density of 450 people per square mile.
What is the median household income in ZIP code 78666?
The median household income in ZIP code 78666 is $52,432, below the national median of ~$75,000.
What timezone is ZIP code 78666 in?
ZIP code 78666 observes the CST timezone.