ZIP 18104 is both Zillow’s ZIP market identifier and a match to a Census ZCTA; a ZCTA is a statistical area and is not identical to a USPS delivery ZIP. In June 2026, Zillow’s ZIP-level ZORI was $2,237, up 3.7% from the same month a year earlier. ZORI is a typical observed asking-rent index blended across rental types, so it describes a current market signal rather than a lease offer or every renter’s payment. It is not a bedroom-specific quote for a particular property. Its level sits 36.7% above the $1,637 ACS 2024 five-year median gross rent, a difference that makes the source universe—not just the dollar gap—the central tension in this ZIP.
The historical record supports an upward longer path while leaving room for monthly movement: 69 direct Zillow ZIP observations through June 2026 provide 100% of the intended coverage. Exact same-month changes annualized to 3.7% over one year, 3.4% over three years, and 4.3% over five years. Thus the latest positive year confirms rather than breaks from the longer measured path, although it is not a forecast. Annualized monthly-return variability was 2.9%, and the maximum drawdown was 3.6%, so one current reading merits moderate, not absolute, confidence. Transparent national discovery ranks among history-eligible ZIPs were 767 for momentum, 1,485 for stability, and 802 for balanced performance; lower ranks are higher. These are backward-looking measurements, not investment recommendations.
The bedroom view is deliberately modelled, not a set of measured bedroom rents. Scaling the ZIP ZORI by the local HUD ladder produces modelled monthly estimates of $1,547 for a studio, $1,836 for one bedroom, $2,237 for two bedrooms, $2,857 for three bedrooms, and $3,005 for four bedrooms. HUD’s FY2026 FMR/SAFMR ladder is an administrative, bedroom-specific standard, not asking rent; its local two-bedroom standard is $1,634. The two-bedroom modelled estimate is therefore 36.9% above that HUD benchmark. This alignment is a calculation based on the local ladder, not evidence that units at any bedroom count were observed at those amounts.
A simple income screen sharpens, but does not settle, the affordability question. At a 30% rent-to-income threshold, annual income required to cover the current ZORI is $89,480, compared with a ZCTA median household income of $94,601; annualized asking rent equals 28.4% of that median. This is arithmetic, not advice or an applicant qualification rule, and a household median cannot establish what any renter can pay. In the ACS renter survey, 2,488 of 5,374 renter households reported spending 30% or more of income on gross rent, or 46.3%. That burden measure concerns occupied renter homes and gross rent, which includes selected utilities, rather than current asking rents.
Wider places put the premium in context but cannot substitute for ZIP evidence: Allentown city context had a rent value of $1,732, Lehigh County context $1,842, and the Allentown-Bethlehem-Easton, PA-NJ metro context $1,861. Each is below the ZIP’s current index, yet each refers to a broader scope. On the survey side, Allentown city context had $1,317 median gross rent and 60.9% of renters at or above the burden threshold, while Lehigh County context showed $1,383 and 55.0%, respectively. These comparisons describe context only; differing geographic and source universes preclude treating them as substitutes for a ZIP listing or household outcome.
Housing evidence adds a separate supply lens. The ZCTA counted 19,193 housing units, with a 3.4% overall vacancy rate; 202 vacant units were classified for rent, alongside seasonal and for-sale vacancies. Its structure mix was led by single-family homes, with a smaller large-multifamily segment. These are counts and classifications within the ACS ZCTA rather than a live availability feed. In particular, an overall vacancy rate or a vacant-for-rent count cannot prove availability, condition, price, lease terms, or suitability for a particular unit. The ZCTA’s tenure mix differs from the wider city context, reinforcing why cross-area comparisons need care.
The main limitation is comparability: a blended current asking-rent index, an ACS retrospective survey measure, and a HUD administrative standard answer different questions. Rounding, survey uncertainty, rental-type mix, and the absence of property attributes further limit precision. Before using this ZIP-level evidence for a specific home, verify the advertised rent and bedroom count, whether utilities match the gross-rent concept, the lease term, fees, deposits, concessions, current availability, utility billing responsibility, and the unit’s location and condition. Check the applicable HUD standard separately from any asking price, compare the listing date with the historical endpoint, and retain the source definitions used. Which measure matches the unit, household, and decision being evaluated?
","findings":[{"body":"Zillow recorded a $2,237 June 2026 ZORI for ZIP 18104, while the matched ACS 2024 five-year median gross rent was $1,637. The 36.7% spread should not be read as a pricing error: ZORI blends observed asking rents across rental types, whereas ACS summarizes occupied renter homes and selected utilities. The comparison identifies a source and timing gap requiring listing-level confirmation.","title":"Current asking signal exceeds resident survey rent"},{"body":"The history shows positive same-month annualized change over one, three, and five years, with the latest year moving in the same direction as the longer record. However, 2.9% annualized monthly-return variability and a 3.6% maximum drawdown mean the current index is a useful benchmark, not a precise promise for a specific unit. The fully covered 69-observation series is backward-looking.","title":"Recent increase follows the longer measured direction"},{"body":"Bedroom figures are modelled by applying the local HUD ladder to the ZIP ZORI. The resulting two-bedroom estimate of $2,237 is 36.9% above the $1,634 HUD standard. Neither figure is a measured bedroom-specific asking rent: HUD FMR/SAFMR is an administrative standard, while the estimate inherits the blended character of ZORI. Confirm a listing’s actual bedroom count and price.","title":"Bedroom figures are ladder-based estimates"},{"body":"At the 30% arithmetic screen, the index corresponds to $89,480 in annual income, against a $94,601 ZCTA median household income. Yet ACS reports 46.3% of renter households spending at least 30% of income on gross rent. With a 3.4% overall vacancy rate, aggregate stock and burden statistics describe the area rather than availability or affordability of any individual rental.","title":"Area affordability indicators show mixed evidence"}],"risks":["ZORI is a blended ZIP asking-rent index, ACS is a five-year survey of occupied renter homes with selected utilities, and HUD is an administrative standard; their dollar amounts are not interchangeable.","The matched ZCTA is a statistical geography rather than a USPS delivery ZIP, so ZIP-level figures may not map exactly to a property’s mailing address or service area.","Overall vacancy, vacant-for-rent classifications, and housing-stock totals cannot demonstrate that a particular unit is currently available, properly described, habitable, or offered at the reported rent.","Positive historical changes and discovery ranks are retrospective measurements only; monthly variability and prior drawdown mean they should not be treated as forecasts, investment recommendations, or guarantees."],"qa":[{"a":"They measure different universes and periods. Zillow’s June 2026 ZORI is a typical observed asking-rent index blended across rental types. The ACS 2024 five-year median gross rent summarizes occupied renter homes and includes selected utilities. A current advertised-rent signal can therefore differ from a retrospective resident-payment survey statistic without either source being interchangeable.","q":"Why do Zillow and ACS show different rent levels for 18104?"},{"a":"No. The studio through four-bedroom figures are modelled estimates created by scaling the ZIP ZORI with the local HUD bedroom ladder. They are not measured bedroom rents or a count of current listings. HUD FMR/SAFMR itself is a bedroom-specific administrative standard rather than asking rent, so the figures are best read as a consistent comparison framework.","q":"Are the bedroom rents observed rents?"},{"a":"No. Dividing annualized ZORI by the 30% threshold produces an arithmetic screen, not advice or an applicant qualification rule. It does not account for the rent of a particular unit, household composition, utilities, fees, income sources, credit standards, or a landlord’s process. The ZCTA median income is likewise an area statistic, not a household assessment.","q":"Does the required-income calculation determine whether a household qualifies?"},{"a":"Use it as a backward-looking benchmark for the ZIP rather than a forecast of the listing’s rent. The complete observed history shows a positive longer path but also monthly variability and a prior drawdown. Compare the listing’s advertised rent, date, bedroom count, utilities, fees, lease term, availability, condition, and location with applicable source definitions before drawing a property-level conclusion.","q":"How should the historical record be used when checking a listing?"}],"sources":[{"key":"apartment_list_time_on_market","name":"Apartment List Time on Market — listing liquidity","release":"Apartment List 2026-07","pulledAt":"2026-08-08","url":"https://www.apartmentlist.com/research/category/data-rent-estimates"},{"key":"apartment_list_vacancy","name":"Apartment List Vacancy Index — rental vacancy","release":"Apartment List 2026-07","pulledAt":"2026-08-08","url":"https://www.apartmentlist.com/research/apartment-list-vacancy-index-methodology"},{"key":"census_zcta_facts","name":"Census ACS five-year — ZCTA housing and income","release":"ACS 2024 5-year ZCTA","pulledAt":"2026-08-08","url":"https://api.census.gov/data/2024/acs/acs5.html"},{"key":"hud_zip","name":"HUD USPS crosswalk and Small Area FMRs — ZIP rent fallback","release":"ZIP-CBSA 2025Q4 + SAFMR FY2026","pulledAt":"2026-07-26","url":"https://www.huduser.gov/portal/datasets/usps_crosswalk.html"},{"key":"realtor_county","name":"Realtor.com Economic Research — county listing inventory","release":"county inventory 2026-06","pulledAt":"2026-07-28","url":"https://www.realtor.com/research/data/"},{"key":"redfin","name":"Redfin Data Center — inventory, days on market, and price cuts","release":"metro tracker through 2026-05-01","pulledAt":"2026-07-26","url":"https://www.redfin.com/news/data-center/"},{"key":"redfin_zip","name":"Redfin Data Center — ZIP resale activity and supply","release":"ZIP rolling 3 months through 2026-06-30; updated 2026-07-03","pulledAt":"2026-08-12","url":"https://www.redfin.com/news/data-center/"},{"key":"zillow_county","name":"Zillow ZHVI and ZORI — county values and rents","release":"county ZHVI/ZORI 2026-06","pulledAt":"2026-07-26","url":"https://www.zillow.com/research/data/"},{"key":"zillow_zori","name":"Zillow ZORI — metro market rents","release":"Metro_zori_uc_sfrcondomfr_sm_sa_month.csv","pulledAt":"2026-07-26","url":"https://www.zillow.com/research/data/"},{"key":"zillow_zori_city","name":"Zillow ZORI — city market rents","release":"zillow_zori_city.csv","pulledAt":"2026-07-29","url":"https://www.zillow.com/research/data/"},{"key":"zillow_zori_zip","name":"Zillow ZORI — ZIP market rents","release":"ZORI ZIP 2026-06","pulledAt":"2026-08-08","url":"https://www.zillow.com/research/data/"}],"history":[{"period":"2020-10-01","rent":1595.172153},{"period":"2020-11-01","rent":1636.869912},{"period":"2020-12-01","rent":1627.98359},{"period":"2021-01-01","rent":1650.200035},{"period":"2021-02-01","rent":1664.456077},{"period":"2021-03-01","rent":1704.744781},{"period":"2021-04-01","rent":1733.600799},{"period":"2021-05-01","rent":1768.749756},{"period":"2021-06-01","rent":1808.426719},{"period":"2021-07-01","rent":1860.187565},{"period":"2021-08-01","rent":1898.239037},{"period":"2021-09-01","rent":1933.341468},{"period":"2021-10-01","rent":1963.877199},{"period":"2021-11-01","rent":1978.116618},{"period":"2021-12-01","rent":1987.759355},{"period":"2022-01-01","rent":1995.612189},{"period":"2022-02-01","rent":2018.533897},{"period":"2022-03-01","rent":2030.065753},{"period":"2022-04-01","rent":2030.725453},{"period":"2022-05-01","rent":2019.601452},{"period":"2022-06-01","rent":2010.731547},{"period":"2022-07-01","rent":1987.918062},{"period":"2022-08-01","rent":1987.240541},{"period":"2022-09-01","rent":1986.207075},{"period":"2022-10-01","rent":1979.861049},{"period":"2022-11-01","rent":1957.088987},{"period":"2022-12-01","rent":1969.062573},{"period":"2023-01-01","rent":1976.540385},{"period":"2023-02-01","rent":2002.08487},{"period":"2023-03-01","rent":2010.623186},{"period":"2023-04-01","rent":2017.006955},{"period":"2023-05-01","rent":2025.782271},{"period":"2023-06-01","rent":2022.194182},{"period":"2023-07-01","rent":2028.924939},{"period":"2023-08-01","rent":2046.178258},{"period":"2023-09-01","rent":2038.201839},{"period":"2023-10-01","rent":2036.906188},{"period":"2023-11-01","rent":2032.887548},{"period":"2023-12-01","rent":2052.342045},{"period":"2024-01-01","rent":2068.692799},{"period":"2024-02-01","rent":2059.987311},{"period":"2024-03-01","rent":2061.853395},{"period":"2024-04-01","rent":2077.49929},{"period":"2024-05-01","rent":2090.18875},{"period":"2024-06-01","rent":2112.315039},{"period":"2024-07-01","rent":2118.761564},{"period":"2024-08-01","rent":2132.165776},{"period":"2024-09-01","rent":2140.919019},{"period":"2024-10-01","rent":2149.14238},{"period":"2024-11-01","rent":2163.413875},{"period":"2024-12-01","rent":2167.251154},{"period":"2025-01-01","rent":2154.985294},{"period":"2025-02-01","rent":2143.864983},{"period":"2025-03-01","rent":2139.426139},{"period":"2025-04-01","rent":2153.00087},{"period":"2025-05-01","rent":2167.572355},{"period":"2025-06-01","rent":2158.39469},{"period":"2025-07-01","rent":2166.59512},{"period":"2025-08-01","rent":2160.163604},{"period":"2025-09-01","rent":2169.926383},{"period":"2025-10-01","rent":2178.031458},{"period":"2025-11-01","rent":2186.860311},{"period":"2025-12-01","rent":2184.678562},{"period":"2026-01-01","rent":2197.670832},{"period":"2026-02-01","rent":2218.416724},{"period":"2026-03-01","rent":2233.356895},{"period":"2026-04-01","rent":2228.418467},{"period":"2026-05-01","rent":2224.547043},{"period":"2026-06-01","rent":2237.421856}],"historySummary":{"pointCount":69,"firstPeriod":"2020-10-01","latestPeriod":"2026-06-01","coverageMonths":69,"coverageRatio":1,"changes":{"1":{"years":1,"startPeriod":"2025-06-01","endPeriod":"2026-06-01","startRent":2158.39469,"endRent":2237.421856,"change":0.03661386231449626,"cagr":0.03661386231449626},"3":{"years":3,"startPeriod":"2023-06-01","endPeriod":"2026-06-01","startRent":2022.194182,"endRent":2237.421856,"change":0.10643274316373241,"cagr":0.03428844591749147},"5":{"years":5,"startPeriod":"2021-06-01","endPeriod":"2026-06-01","startRent":1808.426719,"endRent":2237.421856,"change":0.23722008334250888,"cagr":0.04349264479519399}},"maxDrawdown":-0.03626116267524815,"annualizedVolatility":0.02927595955783268,"consecutiveReturnCount":68}}