# Data Dictionary - US EV Charging Infrastructure Buildout - monthly by state, cleaned Parquet

**Units:** vary by `metric` - read the per-row `unit` column (overall: stations / ports).  Times are UTC.

| column | type | description |
|---|---|---|
| `zone` | str | US state (2-letter) |
| `ts` | timestamp (UTC) | Month |
| `metric` | str | Cumulative public stations / DC-fast ports / Level-2 ports |
| `value` | float | Cumulative count as of that month |
| `unit` | str | Unit |
| `res_min` | int | Native resolution (monthly) |

*Source: Alternative Fuels Data Center, U.S. DOE / NREL (via api.data.gov).*