Initial setup: README and structure for TIGER data dumps

.gitignore

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+# Database dumps (stored in releases, not git)
+*.dump
+*.sql.gz
+*.backup
+
+# Temporary files
+*.tmp
+*.log

README.md

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+# TIGER Geocoder Data Dumps
+
+Pre-built PostgreSQL database dumps for the [TIGER/Line Rural Address Geocoder](https://git.supported.systems/mctiger/mctiger).
+
+## Available Dumps
+
+| File | State | Vintage | Size | Description |
+|------|-------|---------|------|-------------|
+| `idaho-tiger-2024.dump` | Idaho (ID) | 2024 | ~297 MB | All 44 counties with edges, featnames, places |
+
+## Quick Start
+
+Instead of downloading and importing raw TIGER/Line shapefiles, restore a pre-built dump:
+
+```bash
+# 1. Download the dump (from releases)
+wget https://git.supported.systems/mctiger/mctiger-data/releases/download/v2024.1/idaho-tiger-2024.dump
+
+# 2. Restore to your PostGIS database
+pg_restore -h localhost -U postgres -d tiger_geocoder idaho-tiger-2024.dump
+```
+
+## What's Included
+
+Each dump contains:
+
+- **tiger_edges** - Road segments with geometries, names, address ranges
+- **tiger_featnames** - Alternate road names and aliases
+- **tiger_places** - City/town boundaries with pre-computed centroids
+- **Indexes** - GiST spatial indexes and GIN trigram indexes (ready to query)
+
+## Creating Your Own Dumps
+
+To create a dump for another state:
+
+```bash
+# 1. Download TIGER/Line data
+tiger-download --state 06  # California
+
+# 2. Import into PostGIS
+tiger-import --state 06
+
+# 3. Create dump
+pg_dump -Fc -h localhost -U postgres tiger_geocoder > california-tiger-2024.dump
+```
+
+## Versioning
+
+Dumps follow the pattern: `{state}-tiger-{year}.dump`
+
+- **Year** matches the TIGER/Line vintage (e.g., 2024)
+- New releases are created when Census Bureau publishes updated data (typically annually)
+
+## License
+
+TIGER/Line data is public domain (US Government work). See [Census Bureau Terms](https://www.census.gov/data/developers/about/terms-of-service.html).