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CondominiumResidential

139 Prospect St

ACTON, MA 01720
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.
Built 200712 units1,690–2,617 ft²
$9M
All units combinedThe sum of our current value estimates for every unit in the building — roughly what the whole building's homes are worth together.
$797K
Median unit valueThe middle unit value in this building by our estimate: half the units are worth more, half less.
$382
Median $/ft²The middle price per square foot across the building's units, by our current estimates. Useful for comparing units of different sizes.

-9.9%vs the Acton ZIP median sale $/ft² ($424)

Sales Performance

$875K
Median sale (12 mo)The middle sale price among this building's units that sold in the last 12 months, from recorded deeds.
+14.2%
1-yr changeHow the building's median sale price over the last 12 months compares with the 12 months before that.
1
Sales (12 mo)Units in this building that sold in the last 12 months, from recorded arms-length deeds.
8.3%
Turnover (12 mo)The share of units that changed hands in the last 12 months. Around 4–6% a year is typical; much higher can signal investor churn or a wave of exits.
This building's own appreciationThe building's own appreciation: for every unit that sold twice (held over a year), we compute its yearly price change between the two sales and take the middle value. This is the cleanest read on how this specific building performs, because it compares each unit to itself.
+1.3%per yeartypical hold 7.4 yrsfrom 10 same-unit resales
Median sale price (yearly, all time)Every recorded arms-length sale in the building since records begin, grouped by year: the bars count sales and the line tracks the median price paid.MedianSales
20082009201520172018202020242025
Sale price per ft² (yearly, all time)The middle price per square foot across the building's units, by our current estimates. Useful for comparing units of different sizes.$/ft²
20082009201520172018202020242025

22 arms-length sales on record for this building.

Unit Mix & Floor PlansThe building's recurring floor plans, found by grouping units with identical beds, baths and square footage in county records. Larger groups are the building's standard layouts; leftover units have one-off sizes.

Every unit: size vs estimated valueEvery unit in the building as one dot: across is its size, up is our current value estimate, and color is its bedroom count. Vertical columns of dots are recurring floor plans; the height spread within a column shows how much floor, view and condition move prices for the same layout.
$479K$627K$776K$924K1,690 ft²1,875 ft²2,061 ft²2,246 ft²2,432 ft²2,617 ft²
2 bd3 bd
2 bed
3 units
3 bed
9 units
Recurring floor plansThe building's recurring floor plans, found by grouping units with identical beds, baths and square footage in county records. Larger groups are the building's standard layouts; leftover units have one-off sizes.
3 bd · 2.5 ba · 2,006 ft²
7 units
3 bd · 2.5 ba · 2,617 ft²
2 units
One-off layouts
3 units

Value DistributionHow the building's units spread across value ranges by our current estimates. A wide spread usually means big differences in size, floor or view.

$479K–$498K
3 units
$761K–$799K
4 units
$835K–$863K
2 units
$868K–$924K
3 units

Ownership & Financing

Owner-occupiedThe share of units where the owner lives in the unit, per county records. The rest are second homes or rentals.100%
Company-ownedUnits owned through an LLC, trust, or other company — a rough proxy for investor ownership.0%
Typical owner tenureThe middle number of years since each unit last changed hands — how long the current owners have been in place.10.4 yrs
Cash purchases (5 yrs)The share of purchases in the last 5 years with no mortgage recorded. High cash share is common in second-home and investor buildings.40%
Avg. loan-to-valueAverage current loan balance against unit value across the building. Low numbers mean owners hold lots of equity — a sign of financial stability.45%
Median owner equityThe middle dollar amount of equity (value minus loans) unit owners hold in this building.$795,340
Median tax billThe middle annual property tax bill among the building's units.$12,303
Pre-foreclosure noticesUnits with an active pre-foreclosure or foreclosure notice on file.0

Recent SalesThe latest recorded arms-length sales in the building, newest first.

Unit 5Oct 30, 2025$875,000Unit 7Aug 5, 2025$780,000Unit 12Jun 9, 2025$752,000Unit 10Aug 19, 2024$780,000Unit 2Aug 22, 2022$680,000Unit 2Oct 29, 2020$580,000Unit 7Sep 12, 2018$560,000Unit 1May 26, 2017$553,000Unit 12Apr 30, 2015$515,000Unit 9Jan 29, 2015$183,600

Values are TopHap estimates, not appraisals. Sales, ownership and tax figures come from recorded county documents via ATTOM and can lag by several weeks.

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

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%

All UnitsEvery property record the county has at this street address, such as the units in a condo building. Prices shown are our estimates, not asking prices.

139 Prospect St
3 bd · 2.5 ba · 2,006 ft²
$799K
139 Prospect St # 2
3 bd · 2.5 ba · 2,006 ft²
$863K
139 Prospect St
2 bd · 2.5 ba · 1,690 ft²
$498K
139 Prospect St # 4
3 bd · 2.5 ba · 2,006 ft²
$761K
139 Prospect St # 5
3 bd · 2.5 ba · 2,617 ft²
$888K
139 Prospect St # 6
2 bd · 2.5 ba · 2,006 ft²
$479K
139 Prospect St # 7
2 bd · 2.5 ba · 2,042 ft²
$796K
139 Prospect St # 8
3 bd · 2.5 ba · 2,617 ft²
$924K
139 Prospect St
3 bd · 2.5 ba · 2,006 ft²
$480K
139 Prospect St # 10
3 bd · 2.5 ba · 2,006 ft²
$835K
139 Prospect St # 11
3 bd · 2.5 ba · 2,006 ft²
$868K
139 Prospect St # 12
3 bd · 2.5 ba · 2,006 ft²
$772K

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

About 139 Prospect St

How many units are in 139 Prospect St, Acton, MA?

139 Prospect St, Acton, MA has 12 residential units across built in 2007, according to county assessor records.

What is a unit at 139 Prospect St, Acton, MA worth?

The median TopHap Estimate across the 12 units at 139 Prospect St, Acton, MA is $797,457. That works out to $382 per square foot. Units run from 1,690 to 2,617 square feet. Estimates are modelled from recorded sales and assessments, not appraisals.

Is 139 Prospect St, Acton, MA expensive for Acton?

Units at 139 Prospect St, Acton, MA carry a median of $382 per square foot, 10% below the Acton median of $424 per square foot.

How often do units sell at 139 Prospect St, Acton, MA?

1 units at 139 Prospect St, Acton, MA sold in the last 12 months, out of 22 recorded arms-length sales all time. That is a turnover rate of 8.3% of the building per year. The median sale over that period was $875K.

Have units at 139 Prospect St, Acton, MA appreciated?

Across 10 repeat sales of the same unit, 139 Prospect St, Acton, MA returned a median 1.3% per year. Because each pair is the same unit bought and sold, the figure is not distorted by which units traded. The median owner held for 7.4 years.

What floor plans does 139 Prospect St, Acton, MA have?

The most common plan at 139 Prospect St, Acton, MA is a 3-bedroom of 2,006 square feet, repeated 7 times, with a median estimate of $799,000. TopHap identifies 2 recurring plans in the building.

Closest homes

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Assigned schools

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