2. 421 Mapleton Ave Apt A Boulder CO
421 Mapleton Ave Apt A Boulder CO

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421 Mapleton Ave APT a Boulder, CO

421 Mapleton Ave APT a Boulder, CO 80304 was built in 1906 and last sold for $727,000. The property has a lot size of 25 Sq Ft lot and is listed as a Condominium. The property is currently not for sale. Current estimates place the value near 621,000, reflecting a 8% change over the past year, with 1 beds, 1.75 baths, and approximately 618 sq ft of living space. If you are looking to buy or rent a property, use USPhoneBook's property database to avoid rental scams, understand tax liabilities, and get a sense of the property's value over time. You can also check out the neighborhood section and see nearby homes, last sold for prices, tax records and more.
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Public Facts

$727,000
Last sold Jul 24, 2026
1
Beds
1.75
Baths
618
Sqft
Off Market
$621,000 estimated value
Built in 1906
$1,005/sqft
25 lot sqft
$645 HOA fees

Property characteristics

Property type
Residential
Zoning type
Condominium
APN
R0140895
Parking
1
Subdivision
Mapleton Avenue Condominiums - Bo
Heating
Hot Water
Stories
1

Property History

Over the last 12 months, the sales price of 421 Mapleton Ave APT a Boulder, CO 80304 has increased by 8%.

Price History

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Year Price Price/Sq Ft
2026 $ 633,000 8 % $ 1,024
2025 $ 584,000 3 % $ 945
2024 $ 566,000 2 % $ 916
2023 $ 554,000 -19 % $ 896
2022 $ 684,000 16 % $ 1,107
2021 $ 585,000 ---- $ 947

Tax History

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Year Taxes Assesments
2026 ---- $ 46,900
2025 $ 4,110 32 %
2024 $ 3,110 1 % $ 43,106
2023 $ 3,056 -3 % $ 35,387
2022 $ 3,164 ---- $ 34,076
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Owner

Michael Haag Michael Allen Haag , Age 53

Lives at 421 Mapleton Ave, Apt A, Boulder, CO 80304-3984
Relatives: Cachet Cobb, Caleb Haag, Heather Haag, Jacob Haag, Johanna Haag, Micah Haag, Natalie Haag, Nathan Haag
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People Living at 421 Mapleton Ave #A Boulder, CO

Charles Mason Charles Douglas Mason , Age 59

Lives at 511 2nd AVE, Lyons, CO 80540-5063 Lyons CO 80540 511 2nd AVE
Prior addresses: Po Box 1751, Lyons, CO 80540-1751 Lyons CO 80540 Po Box 1751 511 2nd AVE, Unit 9, Lyons, CO 80540-5063 Lyons CO 80540 511 2nd AVE, Unit 9
Relatives: Martina Mason, Carol Mason, Charles Mason, Angela Cole, Ann Mason, Anthony Vern, Bobby Cole, Carmela Pia
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Dan Summers Dan P Summers , Age 33

Lives at 216 Byrne St, Houston, TX 77009-6704 Houston TX 77009 216 Byrne St
Prior addresses: 838 Confidence Dr, Longmont, CO 80504-8470 Longmont CO 80504 838 Confidence Dr Po Box 9664, Chapel Hill, NC 27515-9664 Chapel Hill NC 27515 Po Box 9664 2301 Steel St, Houston, TX 77098-5609 Houston TX 77098 2301 Steel St
Relatives: Carolyn Summers, Elizabeth Summers, Patrick Summers, Carolyn Mancilla, Carolyn Sumners, Christie Reed, Paul Summers, Sally Summers
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Robert Annear Robert David Annear , Age 70

Lives at 2291 Placid Dr, Boulder, CO 80301-5142 Boulder CO 80301 2291 Placid Dr
Prior addresses: 6009 W Parker RD, Ste 149, Plano, TX 75093-8121 Plano TX 75093 6009 W Parker RD, Ste 149 238 Rendezvous Dr, Lafayette, CO 80026-3398 Lafayette CO 80026 238 Rendezvous Dr 2834 Crater Lake Ln, Lafayette, CO 80026-3487 Lafayette CO 80026 2834 Crater Lake Ln
Relatives: Julie Annear, Robert Annear
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Kristina Olsen Kristina Miller Olsen , Age 60

Lives at 249 Spruce St, Boulder, CO 80302-4905 Boulder CO 80302 249 Spruce St
Prior addresses: 305 County Road 494, Grand Lake, CO 80447 Grand Lake CO 80447 305 County Road 494 494 Grand AVE, Grand Lake, CO 80447-5409 Grand Lake CO 80447 494 Grand AVE
Relatives: Nicholas Olsen, Elizabeth Miller, Jody Miller, Kristina Miller, Robert Miller, Susan Olsen, Thomas Miller, Aaron Miller, Aidan Miller
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Susan Jackson Susan Rosewell Jackson , Age 82

Lives at 421 Mapleton Ave, Apt B, Boulder, CO 80304-3984 Boulder CO 80304 421 Mapleton Ave, Apt B
Prior addresses: 421 Mapleton AVE, Apt A, Boulder, CO 80304-3962 Boulder CO 80304 421 Mapleton AVE, Apt A 255 Canyon Blvd, Ste 300, Boulder, CO 80302-4954 Boulder CO 80302 255 Canyon Blvd, Ste 300
Relatives: Jeanne Naber, Jeffrey Jackson, Jennifer Wittemyer, Sandra Rosewell, Amy Russell, Christopher Wittemyer, David Naber, Elizabeth Naber, Francine Ide
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Michael Haag Michael Allen Haag , Age 53

Lives at 421 Mapleton Ave, Apt A, Boulder, CO 80304-3984 Boulder CO 80304 421 Mapleton Ave, Apt A
Prior addresses: Po Box 520, Genoa, NV 89411-0520 Genoa NV 89411 Po Box 520 2211 Spring Grove Dr, Williamsport, PA 17701-1256 Williamsport PA 17701 2211 Spring Grove Dr 1571 Bradley Dr, Boulder, CO 80305-7371 Boulder CO 80305 1571 Bradley Dr
Relatives: Cachet Cobb, Caleb Haag, Heather Haag, Jacob Haag, Johanna Haag, Micah Haag, Natalie Haag, Nathan Haag
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Elizabeth Summers Elizabeth A Summers , Age 30

Lives at 8180 Manitoba St, Apt 340, Playa Del Rey, CA 90293-8647 Playa Del Rey CA 90293 8180 Manitoba St, Apt 340
Prior addresses: 3165 Sawtelle BLVD, Apt 107, Los Angeles, CA 90066-1419 Los Angeles CA 90066 3165 Sawtelle BLVD, Apt 107 9664 PO Box, Chapel Hill, NC 27515-9664 Chapel Hill NC 27515 9664 PO Box 124 S Boundary ST, Chapel Hill, NC 27514-3808 Chapel Hill NC 27514 124 S Boundary ST
Relatives: Carolyn Summers, Dan Summers, Patrick Summers, Carolyn Mancilla, Carolyn Sumners, Christie Reed, Paul Summers, Sally Summers
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Daniel Forman Daniel Jay Forman , Age 50

Lives at 861 Grant Pl, Boulder, CO 80302-7414 Boulder CO 80302 861 Grant Pl
Prior addresses: 500 Kalmia Ave, Boulder, CO 80304-1734 Boulder CO 80304 500 Kalmia Ave 1030 E Circle Dr, Milwaukee, WI 53217-5363 Milwaukee WI 53217 1030 E Circle Dr
Relatives: David Reese, Kathy Wilfong, Shari Hellman, Adam Hellman, Charles Haney, Emma Hellman, Gina Reese
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Neighbors

421 Mapleton Ave #B
Boulder, CO
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417 Mapleton Ave #B
Boulder, CO
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417 Mapleton Ave #C
Boulder, CO
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417 Mapleton Ave #A
Boulder, CO
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FAQs

Who lives at 421 Mapleton Ave #A, Boulder, CO 80304?
According to our records, the current person living in 421 Mapleton Ave #A is Michael Haag.
Is this property currently for sale?
The property is not for sale and last sold for $727,000 on Jul 24, 2026. Use USPhoneBook to review nearby listings or compare similar homes in the area.
What is the estimated value of this property?
The estimated value is $621,000, reflecting a 8% change over the past year. You can explore price history and tax records to see how the value has changed over time.
How big is this property?
It features approximately 618 sq ft of living space on a 25 sq ft lot, built in 1906 and classified as a Condominium.
What nearby properties can I compare this to?
Nearby homes include 421 Mapleton Ave #B, 417 Mapleton Ave #B, and 417 Mapleton Ave #C, each with its own property report to help compare size, value, and residents.