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TownhouseResidential
$682,890$544 / ft²
TopHap EstimateOur estimate of what this home would sell for today, based on nearby sales, the home's size and features, and local price trends. It is a starting point, not an appraisal.· confidence 90How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Oct 21, 2026
Last sold for $270,000 on Nov 28, 2000

4278 COMET CIR

UNION CITY, CA 94587
3
Beds
1.5
Baths
1,255 ft²
Living AreaTotal finished area of the structures, from county records. Some counties include shared space like hallways or a building gym, so it may not match a listing.
1,474 ft²
Lot SizeThe size of the land the home sits on, from county records.
1972
Year BuiltThe year the home was originally built, according to county records.
2
StoriesHow many floors the home has above ground.
6
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.

Valuation

$683K
$617K low$749K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$270,000 · Nov 28, 2000

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$5,971 (2025)
Assessed ValueThe value the county assigns to this home to calculate property tax. It is often lower than what the home would sell for.$414,951 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$124,485
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$290,466
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$406,816
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$669,420

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Townhouse
StyleThe architectural style of the home, such as ranch or colonial.Custom Design
CountyALAMEDA
Effective Year BuiltAn adjusted build year that accounts for condition and major remodels. A big renovation can make a home count as newer than it is.1973
Lot (acres)The size of the land the home sits on, from county records.0.03
ConstructionThe main material the home's frame and walls are built from.Wood (Unspecified)
HeatingThe type of heating system in the home.Forced Air With Air Conditioning
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(5)

Sales and refinances filed with the county for this home. Not every transfer is a normal sale, so check the type before comparing prices.

Assigned SchoolsThe public schools this address is zoned for. Boundaries change, so confirm with the district before you count on it.

M
Itliong-Vera Cruz Middle SchoolB+
Middle · Grades 6–8 · 0.7 mi
E
Pioneer Elementary SchoolB+
Elementary · Grades KG–5 · 0.9 mi
H
James Logan High SchoolB+
High · Grades 9–12 · 2.4 mi

District: New Haven Unified School District

Neighborhood · ZIP 94587These are comparison scores, not percentages. 100 equals the national average, so 150 means about 50% above average.

CrimeLocal crime compared with the rest of the country, where 100 is average. It reflects things like population density, income, and how crime gets reported.43
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.87
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.552

Index scale: 100 = US average (tick). Lower is better.

Homes occupiedThe share of homes here that someone lives in. The rest sit empty, including vacation and for-sale homes.98%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.30%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.6.8%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.4%
PopulationHow many people live in this area.66,162
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.5,241 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$129,537
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$155,780
Average tempThe average temperature here across a full year.58°F
Annual precipHow much rain and melted snow falls here in a typical year.19 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.78%

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Data by ATTOM. Valuations are automated estimates, not appraisals. Photos from Google Street View and may not depict the current property state.

How this home compares

4278 Comet Cir measured against every home in its neighborhood, its ZIP code and its county, using county assessor records refreshed nightly. A home can stand out in one of those areas and look ordinary in another, because each one holds a different mix of homes.

  • Worth less than 86% of homes in Union City 94587
  • Costs less per square foot than 92% of homes in Union City 94587
  • Smaller than 78% of homes in Union City 94587
  • Has a smaller lot than 98% of homes in Union City 94587

What homes are worth in Union City 94587

Each bar is how many homes fall in that price range. The marker is this home.

This home
$447K$2.2M

This home is worth more than 14% of homes in Union City 94587.

How it measures up in Union City 94587

The dot is this home. The mark in the middle is the typical home in Union City 94587.

Estimated value$682,890
CheaperTypical $1,243,262Pricier

Pricier than 14% of homes nearby

Price per ft²$544
CheaperTypical $730Pricier

Pricier than 8% of homes nearby

Living area1,255 ft²
SmallerTypical 1,566 ft²Bigger

Bigger than 22% of homes nearby

Lot size1,474 ft²
SmallerTypical 0.14 acBigger

Bigger than 2% of homes nearby

Year built1972
OlderTypical 1977Newer

Newer than 38% of homes nearby

How 4278 Comet Cir ranks against every home in each area.
MeasureThis homeUnion City 94587Alameda County
Estimated valuepricier than$682,89014% of homes22% of homes
Price per ft²pricier than$5448% of homes26% of homes
Living areabigger than1,255 ft²22% of homes30% of homes
Lot sizebigger than1,474 ft²2% of homes3% of homes
Year builtnewer than197238% of homes61% of homes

About 4278 Comet Cir

How much is 4278 Comet Cir, Union City, CA worth?

The TopHap Estimate for 4278 Comet Cir, Union City, CA is $682,890 as of Oct 21, 2026. The likely range is $617,006 to $748,774. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 4278 Comet Cir, Union City, CA last sell?

4278 Comet Cir, Union City, CA last sold on Nov 28, 2000 for $270,000, according to the county's recorded deed. TopHap holds 2 recorded sales for this parcel.

How big is 4278 Comet Cir, Union City, CA?

4278 Comet Cir, Union City, CA has 3 bedrooms, 1.5 bathrooms, 1,255 square feet of living space and a 0.03-acre lot.

When was 4278 Comet Cir, Union City, CA built?

4278 Comet Cir, Union City, CA was built in 1972, making it 54 years old. It is a custom design home. The building has 2 stories.

What schools serve 4278 Comet Cir, Union City, CA?

4278 Comet Cir, Union City, CA is assigned to Itliong-Vera Cruz Middle School (middle), rated B+; Pioneer Elementary School (elementary), rated B+; James Logan High School (high), rated B+. All sit in New Haven Unified School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 4278 Comet Cir, Union City, CA compare to other homes in Union City 94587?

Among the 17,568 homes in Union City 94587, it is worth more than 14% of them ($682,890 against a typical $1,243,262), its price per square foot is higher than 8% of them ($544 against a typical $730), it is bigger than 22% of them (1,255 ft² against a typical 1,566 ft²), its lot is bigger than 2% of them (1,474 ft² against a typical 0.14 ac) and it is newer than 38% of them (1972 against a typical 1977). Measured against all of Alameda County, it is worth more than 22% of homes there. These shares are recounted nightly from the full county assessor record for each area, not from active listings.

What are the property taxes on 4278 Comet Cir, Union City, CA?

The 2025 property tax bill for 4278 Comet Cir, Union City, CA was $5,971. The county assessed it at $414,951.

More homes on Comet Cir

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