WASHINGTON, D.C., MARCH 2, 2026 — Forty-two of the 50 largest U.S. housing markets are less affordable in 2024 than they were in 2018, according to the newly released Polygon Affordability Index (PAI), developed by Polygon Research.
Built entirely on loan-level data from the Home Mortgage Disclosure Act (HMDA), the Polygon Affordability Index measures housing affordability using actual originated mortgage transactions rather than survey-based estimates or modeled median household assumptions. The analysis applies a consistent methodology across 2018 and 2024 and focuses on purchase mortgages in the 50 largest U.S. mortgage markets.
Traditional affordability indexes use median assumptions. PAI captures the lived experience of real borrowers in actual transactions, in every community across the country. - Greg Oliven, Chief Technology Officer, Polygon Research
Among the findings:
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The Polygon Affordability Index (PAI) is an interactive housing affordability measure built entirely on HMDA loan-level data. Markets are scored on a 0–100 scale, where higher values indicate greater affordability.
The index combines three components:
Taking the available native HMDA data, monthly principal and interest payments are calculated as a percentage of borrower monthly income.
Price Burden is calculated as property value relative to annual borrower income.
Down payment burden is the required down payment as a percentage of borrower annual income
The analysis includes fixed-rate, first-lien, closed-end purchase loans for 1–4 family primary residences that were originated during the study years. Transactions with reported property values or applicant incomes above $100 million are excluded to remove potential data-entry outliers.
Unlike traditional affordability indexes, which rely on survey estimates or median household modeling, PAI reflects the lived experience of borrowers based on actual mortgage transactions. The index is fully interactive within HMDAVision, Polygon Research’s mortgage market intelligence platform. Users can analyze affordability at national, state, metropolitan, county, and census tract levels and filter results by borrower income tier, age, race, ethnicity, and loan characteristics. Data coverage is consistent from 2018 forward.
Full 50-market ranking (sortable table): https://www.polygonresearch.com/affordability-index
A 90-second overview video introducing the index is available on YouTube.
A webinar replay is also available on demand.
Polygon Research finds 42 of 50 largest U.S. housing markets are less affordable than in 2018, based on HMDA mortgage transaction data.
WASHINGTON, D.C., MARCH 2, 2026 — Forty-two of the 50 largest U.S. housing markets are less affordable in 2024 than they were in 2018, according to the newly released Polygon Affordability Index (PAI), developed by Polygon Research.
Built entirely on loan-level data from the Home Mortgage Disclosure Act (HMDA), the Polygon Affordability Index measures housing affordability using actual originated mortgage transactions rather than survey-based estimates or modeled median household assumptions. The analysis applies a consistent methodology across 2018 and 2024 and focuses on purchase mortgages in the 50 largest U.S. mortgage markets.
Traditional affordability indexes use median assumptions. PAI captures the lived experience of real borrowers in actual transactions, in every community across the country. - Greg Oliven, Chief Technology Officer, Polygon Research
Among the findings:
________________________________________
The Polygon Affordability Index (PAI) is an interactive housing affordability measure built entirely on HMDA loan-level data. Markets are scored on a 0–100 scale, where higher values indicate greater affordability.
The index combines three components:
Taking the available native HMDA data, monthly principal and interest payments are calculated as a percentage of borrower monthly income.
Price Burden is calculated as property value relative to annual borrower income.
Down payment burden is the required down payment as a percentage of borrower annual income
The analysis includes fixed-rate, first-lien, closed-end purchase loans for 1–4 family primary residences that were originated during the study years. Transactions with reported property values or applicant incomes above $100 million are excluded to remove potential data-entry outliers.
Unlike traditional affordability indexes, which rely on survey estimates or median household modeling, PAI reflects the lived experience of borrowers based on actual mortgage transactions. The index is fully interactive within HMDAVision, Polygon Research’s mortgage market intelligence platform. Users can analyze affordability at national, state, metropolitan, county, and census tract levels and filter results by borrower income tier, age, race, ethnicity, and loan characteristics. Data coverage is consistent from 2018 forward.
Full 50-market ranking (sortable table): https://www.polygonresearch.com/affordability-index
A 90-second overview video introducing the index is available on YouTube.
A webinar replay is also available on demand.
42 of the 50 largest U.S. housing markets are less affordable in 2024 than they were in 2018. Boise recorded the steepest overall decline, with its PAI score falling 8.5 points (from 61.4 to 52.9) and down payment burden surging from 61.5% to 87.2% of annual borrower income. Mid-size Midwest markets including Columbus, Cincinnati, Indianapolis, Kansas City, Louisville, and Milwaukee each declined by more than six points, reflecting significant erosion in borrower purchasing power. Seattle ranked as the least affordable major market overall, with monthly mortgage payments consuming 26.6% of borrower income in 2024.
42 of the 50 largest U.S. housing markets are less affordable in 2024 than they were in 2018. Boise recorded the steepest overall decline, with its PAI score falling 8.5 points (from 61.4 to 52.9) and down payment burden surging from 61.5% to 87.2% of annual borrower income. Mid-size Midwest markets including Columbus, Cincinnati, Indianapolis, Kansas City, Louisville, and Milwaukee each declined by more than six points, reflecting significant erosion in borrower purchasing power. Seattle ranked as the least affordable major market overall, with monthly mortgage payments consuming 26.6% of borrower income in 2024.
Los Angeles and San Francisco were among the few markets that posted modest improvements in their overall PAI scores between 2018 and 2024. These gains reflect changes in borrower income relative to loan size among the households that were actually transacting during the period not a broad improvement in access to homeownership. The PAI measures the experience of borrowers who successfully originated loans, so improvements in high-cost markets should be interpreted carefully: they may reflect a compositional shift toward higher-income borrowers rather than a genuine expansion of affordability.
Because the PAI is built from actual mortgage transactions rather than modeled estimates, it can surface affordability dynamics that aggregate measures obscure. Boston's down payment burden reached 96.2% of annual borrower income in 2024, a savings barrier that monthly payment ratios alone would not capture. The PAI is also interactive inside HMDAVision, where users can filter results by borrower income tier, age, race, ethnicity, and loan characteristics at the national, state, metro, county, and census tract level. This makes it possible to analyze affordability not just for the average borrower, but for specific communities including Hispanic homebuyers, first-time buyers, and lower-income households.