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CondominiumResidential
$868,008$332 / 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 88How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Sep 24, 2026
Last sold for $875,000 on Oct 30, 2025

139 PROSPECT ST

ACTON, MA 01720
Building report
3
Beds
2.5
Baths
2,617 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.
2.87 ac
Lot SizeThe size of the land the home sits on, from county records.
2007
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

$868K
$768K low$968K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$875,000 · Oct 30, 2025

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$13,698 (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.$798,700 (2025)
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$798,700
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$911,525

Climate Risk

Overall riskThe average of the five hazard scores below, on a 0 to 100 scale. Higher means greater projected risk over the coming decades.41
1
FloodProjected flooding risk from rivers, heavy rain, and storm surge, scored 0 to 100. Higher is riskier.
17
WildfireProjected wildfire risk, scored 0 to 100, based on how much land burns in a typical year. Higher is riskier.
60
HeatProjected heat risk, scored 0 to 100, based on how many extremely hot days a year are expected. Higher is riskier.
95
StormProjected risk from heavy rainstorms, scored 0 to 100, based on how often extreme rainfall is expected. Higher is riskier.
33
DroughtProjected water shortage risk, scored 0 to 100. Higher means more strain on the local water supply.
FEMA Flood ZoneFEMA's flood zone for this address. Zones starting with A or V are high risk, and lenders usually require flood insurance there.minimal

Scores 0–100; higher = greater projected risk.

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Condominium
CountyMIDDLESEX
HeatingThe type of heating system in the home.Forced Air With Air Conditioning
CoolingThe type of cooling or air conditioning in the home.Yes
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
R. J. Grey Junior High SchoolA
Middle · Grades 7–8 · 0.2 mi
E
Merriam Elementary SchoolB
Elementary · Grades KG–6 · 0.3 mi
H
Acton - Boxborough Regional High SchoolA
High · Grades 9–12 · 0.4 mi

District: Acton-Boxborough School District

Neighborhood · ZIP 01720These 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.71
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.104
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.72

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.97%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.33%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.2.6%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.3%
PopulationHow many people live in this area.24,473
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.1,210 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$148,952
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$187,397
Average tempThe average temperature here across a full year.48°F
Annual precipHow much rain and melted snow falls here in a typical year.47 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.58%

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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

139 Prospect St 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.

  • Costs less per square foot than 92% of homes in Acton 01720
  • Bigger than 77% of homes in Middlesex County
  • Has a bigger lot than 91% of homes in Middlesex County
  • Newer than 93% of homes in Middlesex County

What homes are worth in Acton 01720

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

This home
$227K$1.7M

This home is worth more than 50% of homes in Acton 01720.

How it measures up in Acton 01720

The dot is this home. The mark in the middle is the typical home in Acton 01720.

Estimated value$868,008
CheaperTypical $865,464Pricier

Pricier than 50% of homes nearby

Price per ft²$332
CheaperTypical $412Pricier

Pricier than 8% of homes nearby

Living area2,617 ft²
SmallerTypical 2,083 ft²Bigger

Bigger than 74% of homes nearby

Lot size2.87 ac
SmallerTypical 0.71 acBigger

Bigger than 79% of homes nearby

Year built2007
OlderTypical 1971Newer

Newer than 90% of homes nearby

How 139 Prospect St ranks against every home in each area.
MeasureThis homeActon 01720Middlesex County
Estimated valuepricier than$868,00850% of homes60% of homes
Price per ft²pricier than$3328% of homes15% of homes
Living areabigger than2,617 ft²74% of homes77% of homes
Lot sizebigger than2.87 ac79% of homes91% of homes
Year builtnewer than200790% of homes93% of homes

About 139 Prospect St

How much is 139 Prospect St, Acton, MA worth?

The TopHap Estimate for 139 Prospect St, Acton, MA is $868,008 as of Sep 24, 2026. The likely range is $767,953 to $968,063. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 139 Prospect St, Acton, MA last sell?

139 Prospect St, Acton, MA last sold on Oct 30, 2025 for $875,000, according to the county's recorded deed. TopHap holds 3 recorded sales for this parcel.

How big is 139 Prospect St, Acton, MA?

139 Prospect St, Acton, MA has 3 bedrooms, 2.5 bathrooms and 2,617 square feet of living space.

When was 139 Prospect St, Acton, MA built?

139 Prospect St, Acton, MA was built in 2007, making it 19 years old. The building has 2 stories.

What schools serve 139 Prospect St, Acton, MA?

139 Prospect St, Acton, MA is assigned to R. J. Grey Junior High School (middle), rated A; Merriam Elementary School (elementary), rated B; Acton - Boxborough Regional High School (high), rated A. All sit in Acton-Boxborough School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 139 Prospect St, Acton, MA compare to other homes in Acton 01720?

Among the 7,508 homes in Acton 01720, it is worth more than 50% of them ($868,008 against a typical $865,464), its price per square foot is higher than 8% of them ($332 against a typical $412), it is bigger than 74% of them (2,617 ft² against a typical 2,083 ft²), its lot is bigger than 79% of them (2.87 ac against a typical 0.71 ac) and it is newer than 90% of them (2007 against a typical 1971). Measured against all of Middlesex County, it is worth more than 60% 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 139 Prospect St, Acton, MA?

The 2025 property tax bill for 139 Prospect St, Acton, MA was $13,698. The county assessed it at $798,700.

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