99128 ZIP Code — Farmington, WA

Whitman County, Washington

ZIP code 99128 is located in Farmington, Washington, within Whitman County. It covers approximately 59.49 square miles and serves a population of 289 residents. This is a standard ZIP code in the Pacific (PT) timezone, served by area code 509.

About ZIP code 99128

The housing stock consists of predominantly single-family detached homes. Most homes were built in the pre-1940, giving the area an established character. Median home value is $265,600. Owner-occupancy is high at 85%, well above the national average.

Median household income is $57,143. 36% of households receive Social Security income, suggesting a notable retiree or disability population.

The dominant occupation class is management, business, and professional, with education and healthcare as the leading industry. The average commute of 27 minutes is near the national average.

Educational attainment is near the national average, with 32% of residents holding a bachelor's degree or higher.

Overall, ZIP code 99128 reflects a community defined by high homeownership and a significant Social Security-dependent population.

289

population

59.49

sq mi land

Standard

ZIP type

Pacific (PT)

timezone

99128 ZIP code map

Cities in ZIP code 99128

Below are the cities the US Postal Service accepts for ZIP code 99128. Using any city not on this list may result in mail delivery delays.

City	Status
Farmington	Preferred

Nearby ZIP codes

99104 Belmont (1.7 mi) 99130 Garfield (6.1 mi) 99158 Oakesdale (6.7 mi) 83824 Desmet (10.3 mi) 99033 Tekoa (11.2 mi) 83855 Potlatch (11.7 mi) 99161 Palouse (13.3 mi) 83870 Tensed (13.9 mi) 99018 Latah (14.8 mi) 83872 Viola (16.9 mi) 99170 Rosalia (17.6 mi) 83851 Plummer (18.9 mi)

Demographics updated 05/2026

Population
Total population	289
Population density	5 / sq mi
State FIPS	53
County FIPS	075

Geography
Land area	59.49 sq mi
Water area	0.00 sq mi
Latitude	47.0843
Longitude	-117.1267
Timezone	Pacific (PT)
Area code	509

Total population by age

Gender

Race & ethnicity

Economics updated 05/2026

Household income

Income range	This ZIP	County avg	State avg
Under $50k	39.6%	55.9%	31.7%
$50k – $100k	21.3%	24.5%	30.6%
$100k – $200k	19.5%	15.6%	27.1%
Over $200k	19.5%	4.0%	10.6%

Demographics & statistics

289

Population

People per sq mi

49.8

Median age

$57,143

Median household income

$37,322

Per capita income

$265,600

Median home value

$550

Median monthly rent

85.4%

Home ownership

10.4%

Poverty rate

4.5%

Unemployment

140

Housing units

31.7%

Bachelor's or higher

Age distribution

Male Female

Under 5

5–9

10–14

15–19

20–24

25–34

35–44

45–54

55–59

60–64

65–74

75–84

85+

← Male

Female →

Age summary

Group	Count	%
Under 18	58	20.1%
18 and over	231	79.9%
65 and over	67	23.2%
Median age	49.8 years

Race & ethnicity

White 91.9%

Asian 2.4%

Hispanic or Latino 2%

American Indian / Alaska Native 1.7%

Two or more races 1.4%

Other race 0.7%

Group	Count	%
White	271	91.9%
Asian	7	2.4%
Hispanic or Latino	6	2%
American Indian / Alaska Native	5	1.7%
Two or more races	4	1.4%
Other race	2	0.7%

Household income

Income range	This ZIP	County avg	State avg
Under $50k	39.6%	55.9%	31.7%
$50k – $100k	21.3%	24.5%	30.6%
$100k – $200k	19.5%	15.6%	27.1%
Over $200k	19.5%	4.0%	10.6%

Under $10k 16.2%

$10k–$15k 3.1%

$15k–$25k 6.2%

$25k–$35k 8.5%

$35k–$50k 9.2%

$50k–$75k 21.5%

$75k–$100k 7.7%

$100k–$150k 14.6%

$150k–$200k 2.3%

$200k+ 10.8%

Range	% of households
Under $10k	16.2%
$10k–$15k	3.1%
$15k–$25k	6.2%
$25k–$35k	8.5%
$35k–$50k	9.2%
$50k–$75k	21.5%
$75k–$100k	7.7%
$100k–$150k	14.6%
$150k–$200k	2.3%
$200k+	10.8%
Median income	$57,143

Housing

Home values

Under $50k 9.9%

$50k–$100k 11.7%

$100k–$150k 4.5%

$150k–$200k 8.1%

$200k–$300k 30.6%

$300k–$500k 19.8%

$500k–$1M 15.3%

Housing overview

Metric	Value
Median home value	$265,600
Median rent / month	$550
Owner occupied	85.4%
Renter occupied	14.6%
Vacant	18.2%
Single-family detached	84.3%
Large apartment buildings	0.0%
Mobile homes	14.5%
Median rooms	5.9
Avg household size (owned)	2.23

Year built

Era	%
2020 or later	0.0%
2010–2019	1.9%
2000–2009	10.1%
1990–1999	2.5%
1980–1989	5.0%
1970–1979	8.2%
1960–1969	1.9%
1950–1959	9.4%
1940–1949	1.3%
1939 or earlier	59.7%

Bedrooms

Size	% of units
No bedroom (studio)	0.0%
1 bedroom	5.7%
2 bedrooms	28.3%
3 bedrooms	44.7%
4 bedrooms	19.5%
5+ bedrooms	1.9%

Vehicles per household

Vehicles	% of households
No vehicle	3.1%
1 vehicle	20.0%
2 vehicles	33.1%
3 or more	43.8%

Heating fuel

Fuel type	%
Utility gas	0.8%
Electricity	48.5%
Propane / LP gas	2.3%
Fuel oil	16.2%
Wood	26.9%

Households & families

Household type	Count	%
Married-couple family	72	55.4%
Cohabiting couple	0	0.0%
Male householder, no spouse	42	32.3%
Female householder, no spouse	16	12.3%
Households with children under 18	22	16.9%
Households with seniors (65+)	52	40.0%
Average household size	2.22

Marital status

Status	Male	Female
Never married	13.3%	13.1%
Married	60.7%	69.2%
Separated	5.9%	0.0%
Widowed	0.0%	10.3%
Divorced	20.0%	7.5%

Education

Less than 9th grade 1.3%

Some HS, no diploma 1.3%

HS graduate 23.2%

Some college, no degree 26.3%

Associate's degree 16.1%

Bachelor's degree 26.3%

Graduate / professional 5.4%

Metric	%
HS diploma or higher	97.3%
Bachelor's or higher	31.7%

School enrollment (ages 3–17)

Type	Count	%
Nursery / preschool	5	10.4%
Kindergarten	2	4.2%
Elementary school	26	54.2%
High school	15	31.3%
College / grad school	0	0.0%

Employment

Industry of employment

Education & healthcare 37.0%

Agriculture & mining 14.2%

Professional & management 13.4%

Wholesale trade 10.2%

Other services 7.9%

Manufacturing 5.5%

Public administration 4.7%

Retail trade 3.1%

Construction 1.6%

Transportation & utilities 1.6%

Arts, food & hospitality 0.8%

Occupation

Category	%
Management, business & arts	46.5%
Service	14.2%
Sales & office	17.3%
Natural resources & construction	7.1%
Production & transportation	15.0%

Employment type

Type	%
Private sector	63.8%
Government	29.1%
Self-employed	7.1%
Unpaid family workers	0.0%

Commute

Method	%
Drive alone	59.7%
Carpool	6.5%
Public transit	0.0%
Walk	4.8%
Work from home	19.4%
Other means	9.7%
Avg commute (minutes)	27.4

Poverty

All people 10.4%

Under 18 years 0.0%

18 and over 13.0%

Married-couple families 2.8%

Female-led households 0.0%

Income support

Source	% of households
Social Security	36.2%
Retirement income	25.4%
Supplemental Security	11.5%
Cash public assistance	3.1%
Food stamps / SNAP	10.8%

Health indicators

Condition	%
Obesity	31.1%
High blood pressure	34.3%
High cholesterol	34.6%
Diabetes	9.8%
Heart disease	7.5%
Stroke	3.4%
Asthma	10.3%
Arthritis	27.9%
Kidney disease	3.3%
Pulmonary disease	7.0%
Cancer	8.5%

Behavior / access	%
Smoking	14.2%
Binge drinking	16.2%
No physical activity	18.4%
Less than 7 hrs sleep	27.4%
Depression	24.5%
Fair or poor health	13.2%
Poor mental health	13.6%
Poor physical health	10.9%
No health insurance	9.0%
Visited doctor (checkup)	72.2%
Visited dentist	71.6%
Cholesterol screening	90.7%
Teeth loss	10.2%

Veterans & disability

Veterans	Count	%
Civilian veterans	24	10.4%

Disability	%
Any disability	19.4%
Under 18	0.0%
18–64 years	18.3%
65 and over	38.8%

Health insurance coverage

Type	%
Private insurance	67.1%
Public insurance	44.6%
No insurance	0.7%
Uninsured under 19	0.0%

Language & origin

Language spoken at home (age 5+)

Language	Count	%
English only	278	96.2%
Spanish	0	0.0%
Other Indo-European	0	0.0%
Asian & Pacific Islander	0	0.0%
Other languages	0	0.0%

Place of birth & citizenship

Origin	Count	%
Native born (US)	278	96.2%
Born in same state	275	95.2%
Born in different state	169	58.5%
Foreign born	3	1.0%
Naturalized citizen	11	3.8%
Not a US citizen	7	63.6%

Ancestry

Ancestry	Count	%
Polish	33	11.4%
Italian	22	7.6%
French	14	4.8%

Ancestry	Count	%
Arab	8	2.8%
Dutch	5	1.7%
English	3	1%

Technology access

Metric	% of households
Computer access	45.0%
Internet access	84.6%

Source: U.S. Census Bureau, American Community Survey 2025 estimates.

Frequently asked questions about ZIP code 99128

What city is ZIP code 99128 in?

ZIP code 99128 is primarily assigned to Farmington, Washington.

What county is ZIP code 99128 in?

ZIP code 99128 falls within Whitman County, Washington.

Is ZIP code 99128 mostly owner-occupied?

85% of occupied units in ZIP code 99128 are owner-occupied, well above the national average.

Does ZIP code 99128 have a large retiree population?

36% of households in ZIP code 99128 receive Social Security income, suggesting a significant retiree or disability population.

Does ZIP code 99128 have a large veteran population?

10% of civilians in ZIP code 99128 are veterans, above the national average of ~7%.

What is the population of ZIP code 99128?

ZIP code 99128 has an estimated population of 289 residents, with a density of 5 people per square mile.

What timezone is ZIP code 99128 in?

ZIP code 99128 observes the PST timezone.