# Growth benchmarks — sources and fiscal-year alignment

Built by `scripts/build_benchmarks.py` from the raw downloads in `raw/benchmarks/` (pulled Oct 31 2026).
Output: `data/benchmarks_fy.csv` (one row per Metro fiscal year, FY2001–FY2026) and `data/population_cy.csv`.

Metro Nashville's fiscal year runs **July 1 – June 30** and is named for the calendar year in which it ends
(FY2025 = Jul 2024 – Jun 2025).

| Column | Source | Native frequency | FY alignment |
|---|---|---|---|
| pop_davidson | Census Population Estimates Program: 2000–2010 intercensal (`co-est00int-tot.csv`), Vintage 2019 (`co-est2019-alldata.csv`), Vintage 2025 (`co-est2025-alldata.csv`) | July 1 each year | mean of the Jul-1 estimates that open and close the FY (= FY midpoint, ≈ Jan 1). FY2026 closing estimate extrapolated at the 2024→2025 growth rate (`pop_flag`). |
| pop_msa | Census PEP metro files (Vintage 2019 + 2025), Nashville-Davidson–Murfreesboro–Franklin MSA | July 1 | same rule; MSA series starts FY2011 (2000s metro file not pulled). |
| cpi_us | BLS CPI-U all items, US city average, SA (FRED `CPIAUCSL`) | monthly | mean of the 12 months in the FY |
| cpi_south | BLS CPI-U all items, South urban, NSA (FRED `CUUR0300SA0`) | monthly | mean of the 12 months in the FY |
| deflator_slgov | BEA implicit price deflator, state & local government consumption expenditures and gross investment (FRED `A829RD3Q086SBEA`, 2017=100) | quarterly | mean of the 4 quarters in the FY — the "what it costs governments to buy what they buy" deflator |
| eci_slgov_wages | BLS Employment Cost Index, wages & salaries, state & local government (FRED `ECIGVTWAG`) | quarterly | mean of the 4 quarters (series starts 2001; FY2001 has 2 quarters) |
| employed_davidson | BLS LAUS employed residents, Davidson County (FRED `LAUCN470370000000005`) | monthly | mean of the 12 months |
| employed_msa | BLS LAUS employed residents, Nashville MSA (FRED `LAUMT473498000000005`) | monthly | mean of the 12 months |
| personal_income_davidson_k | BEA personal income, Davidson County, $ thousands (FRED `PI47037`) | calendar year | mean of the two CYs the FY straddles; `open_only` flag when the closing CY is not yet published (FY2025 uses CY2024 alone) |
| per_capita_income_davidson | BEA per-capita personal income, Davidson County (FRED `PCPI47037`) | CY | same |
| gdp_davidson_k / real_gdp_davidson_k | BEA county GDP, nominal and chained-2017 $ thousands (FRED `GDPALL47037`, `REALGDPALL47037`) | CY (2001–2024) | same |
| hpi_davidson | FHFA all-transactions house price index, Davidson County (FRED `ATNHPIUS47037A`) | CY | same |
| median_hh_income_davidson | Census SAIPE median household income, Davidson County (FRED `MHITN47037A052NCEN`) | CY | same |

## Population vintage bridge
The 2020 Census counted 715,884 residents in Davidson County, but the Vintage-2019 estimate for July 2019 was
694,144 — the 2010s estimates ran about 2.6 % low by decade's end. To avoid a false jump in FY2020–FY2021,
the 2010–2019 Vintage-2019 values are scaled by a factor that rises linearly from 1.000 (2010) to 1.0259 (2020),
so the series meets the Vintage-2025 base exactly. This is the same idea as the Census Bureau's own intercensal
method, done simply; it moves 2015 up by ~1.3 % and 2019 by ~2.3 %. `population_cy.csv` records the factor per year.

## What each benchmark is for
* **Population** — the plain "more people to serve" denominator.
* **CPI** — household inflation; the public's intuitive yardstick.
* **S&L government deflator / ECI** — the cost of the labor and goods governments actually buy; it has run
  hotter than CPI in some periods and cooler in others, so "real" spending looks different under each.
* **Population × inflation** — the classic cap test (TABOR-style): did spending grow faster than the two combined?
* **Personal income / GDP** — ability to pay and the size of the local economy; spending as a share of income.
* **Employment** — daytime demand for services (commuters, visitors) that population misses.
* **House prices / assessed value** — the property-tax base (assessed value comes from the ACFR tables).

| us_sl_gov_spending_bn | BEA state & local government current expenditures, US total, $ billions SAAR (FRED `SLEXPND`) | quarterly | mean of the 4 quarters — the national peer: how fast state and local governments everywhere grew |
| us_population_k | US resident population, thousands (FRED `POPTHM`) | monthly | mean of the 12 months; divides the line above into a national per-capita series |