ZIP 78664’s clearest signal is a small recent gain set against an uneven multiyear record. At the June 2026 endpoint, Zillow’s ZORI is $1,621. ZORI is a ZIP-level typical observed asking-rent index blended across rental types, so it summarizes advertised-market conditions rather than a quoted rent for a specified home. The supplied history classification is accelerating, but its exact same-month history is mixed: it rose 0.4% over one year, fell at a -1.9% annualized pace across three years, and rose 2.3% annualized across five years. The recent positive direction breaks from the weaker intermediate path while still fitting a positive longer interval; it does not establish a straight-line recovery. History coverage is 99.3%, annualized monthly-return variability is 3.0%, and maximum drawdown is -10.1%. These backward-looking measures reduce the confidence appropriate for a current snapshot. Transparent national discovery ranks among history-eligible ZIPs are 2,457 for momentum, 1,586 for stability, and 2,459 for balanced history; lower ranks are higher, and the ranks are neither forecasts nor investment recommendations.
Source differences are central to interpreting that contrast. The five-digit label is both Zillow’s ZIP market identifier and the matching Census ZCTA; a ZCTA is a Census statistical area and is not identical to a USPS delivery ZIP. The ACS 2024 five-year survey of occupied renter homes reports median gross rent of $1,692 and includes selected utilities. In contrast, ZORI is the blended typical observed asking-rent index; the current index is 4.2% below the ACS median, not necessarily a like-for-like price difference. HUD’s FY2026 two-bedroom FMR is $1,852, so the index is 12.5% below that figure. HUD FMR/SAFMR is an administrative bedroom-specific standard, not asking rent or evidence of a lease payment.
That distinction controls the bedroom view. Scaling ZIP ZORI using the local HUD ladder produces modelled monthly estimates of $1,290 for a studio, $1,367 for a one-bedroom, $1,621 for a two-bedroom, $2,054 for a three-bedroom, and $2,416 for a four-bedroom. They are modelled estimates, never measured bedroom rents: the spread simply applies local HUD bedroom ratios to a blended ZIP index. The associated HUD ladder supplies those ratios, but it remains an administrative standard rather than an offer schedule. A listing can differ because the index blends property types and the model cannot observe the individual unit.
Affordability evidence points to a separate tension between a broad income screen and reported renter burden. Applying the standard 30% share to the ZIP index yields required annual income of $64,840; this is arithmetic, not advice or an applicant qualification rule. The ZCTA’s ACS median household income is $87,417, and the asking-rent-to-income calculation is 22.3%. Separately, ACS reports 5,292 of 10,881 renter-occupied households spending 30% or more of income on gross rent, a 48.6% share. That burden measure uses the ACS gross-rent definition rather than a particular asking rent. Survey uncertainty and differing household circumstances mean it cannot identify who can afford a specific property; it describes surveyed renter households, not prospective tenants.
Stock counts offer scale but do not resolve individual availability. The ACS ZCTA inventory contains 24,497 housing units, including 16,580 single-family units and 2,804 units in large multifamily buildings. It records 1,013 vacant units, an overall 4.1% vacancy rate, of which 253 are classified as vacant for rent. These categories describe a survey inventory rather than active rental listings, and the full vacant count covers uses other than rentals. Neither the vacancy measure nor the for-rent classification proves that a particular unit is available, priced at the ZIP index, or suitable for a given household. The counts instead frame the scale at which the asking-rent and burden statistics should be read.
Wider reference values are higher, but their geography limits the comparison. For wider context only, the Round Rock city-context rent is $1,713.46, the Williamson County context rent is $1,685, and the Austin-Round Rock-Georgetown, TX metro-context rent is $1,653; each exceeds the ZIP-level index. City, county, and metro figures are context values with those respective scopes, not substitutes for a ZIP index or individual-property data. Their difference from the ZIP reading does not establish a premium, discount, cause, or condition for any building, because each wider area aggregates housing beyond this matched geography.
The evidence should therefore be used as a bounded comparison, not as a property-level conclusion. The asking-rent endpoint and ACS survey vintage differ, ACS estimates carry sampling uncertainty, HUD is an administrative standard, and the historical series records past observations rather than future outcomes. For a real listing, concrete checks are the current advertised rent, exact bedroom count, property type, lease term, included utilities, fees or deposits, concessions, listing status, and whether the address falls within the relevant market geography. Those checks are necessary because no source here observes a unit’s executed lease terms, and area-wide burden or vacancy figures cannot prove anything about that unit. The deciding question is which verified listing terms match the household’s own comparison, rather than whether an aggregate metric guarantees an outcome.
","findings":[{"body":"The June 2026 Zillow ZORI reading for ZIP 78664 is $1,621. Same-month changes are 0.4% over one year, -1.9% annualized across three years, and 2.3% annualized across five years. Combined with 3.0% annualized variability and a 10.1% maximum drawdown, the pattern supports a period-specific reading rather than a stable trend claim.","title":"Recent uptick sits inside a mixed history"},{"body":"The studio-through-four-bedroom series is not a set of observed rents. It takes the ZIP-wide blended ZORI and applies local HUD bedroom ratios, yielding modelled estimates. HUD FMR/SAFMR is itself an administrative bedroom-specific standard, so neither the ladder nor its estimates establish what a property actually asks, includes in rent, or leases for.","title":"Bedroom figures are construction-based"},{"body":"The $64,840 annual income figure results from applying a 30% arithmetic screen to the ZIP index. It is not an affordability recommendation or qualification threshold. The ACS burden statistic instead summarizes surveyed renter households paying 30% or more of gross rent, which includes selected utilities and does not determine a particular household’s capacity.","title":"Income screen and burden are distinct"},{"body":"The city, county, and metro rent values are broader-scope context, while ACS vacancy data are survey inventory categories. Neither establishes a building premium, a live listing count, or a unit’s availability. A decision-level comparison needs current property terms, including bedroom count, lease duration, utility treatment, fees, concessions, and listing status.","title":"Context and inventory are not unit evidence"}],"risks":["Zillow’s blended observed asking-rent index, ACS median gross rent for occupied renter homes with selected utilities, and HUD FMR/SAFMR administrative standards are not interchangeable price measures.","The matched ZCTA is a statistical area rather than a USPS delivery ZIP. Its survey estimates may not represent every address labeled 78664, while city, county, and metro benchmarks cover wider areas.","The historical series has high coverage but also monthly-return variability and a material past drawdown. A current index reading cannot establish a future path, lease renewal outcome, or building-specific trend.","Vacant-for-rent and renter-burden counts are area-wide survey classifications. They do not show that a particular home is currently marketed, within a household’s budget, free of concessions, or available on a chosen date."],"qa":[{"a":"ZORI is a ZIP-level typical observed asking-rent index blended across rental types. ACS reports a five-year survey median for occupied renter homes and includes selected utilities. HUD FMR/SAFMR is a bedroom-specific administrative standard. Different populations, definitions, and geographic constructs mean numerical gaps are comparisons, not a common unit-rent measure.","q":"Why does ZORI differ from ACS gross rent and HUD FMR?"},{"a":"No. The estimates start with the single blended ZIP ZORI and scale it by local HUD bedroom ratios. They are explicitly modelled monthly estimates, not measured bedroom rents. The actual unit may differ by property type, exact bedroom count, lease terms, utilities, fees, concessions, and listing status, none of which the model observes.","q":"Are the modelled bedroom figures observed rents?"},{"a":"At the endpoint, the latest same-month change is positive, whereas annualized three-year change is negative and five-year change is positive. That means recent direction breaks from the intermediate path but fits the longer positive period. High coverage improves continuity, while observed variability and maximum drawdown limit confidence in interpreting a current snapshot as persistent.","q":"What does the recent history say about the current rent reading?"},{"a":"No. Vacancy is a ZCTA-wide survey inventory measure, and burden summarizes renter-occupied households under ACS gross-rent definitions. The city, county, and metro rents are broader context. None identifies availability, a unit’s rent, utility inclusion, or a household’s eligibility, so address-specific listing terms remain the needed check.","q":"Can vacancy, burden, or wider context values establish a unit’s availability or affordability?"}],"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 — 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