# N05_E18 1820–2026 Network and Route Crosswalk

**Research date:** 2026-08-09  
**Sector:** `N05_E18` — canonical 24 × 24 grid cell, 37.5–45.0° N and 270–285° E (90–75° W)  
**Anchor:** Merrillville, Indiana, 41.4828° N, 87.3327° W  
**Time bands:** 1800–1950 industrial transition; 2000–present modern baseline  
**Status:** bounded bridge note; no derived score and no `provisional_quadrant`

## Research question

Can a page-verified historical account of the Chicago–Calumet–Lake Michigan route and settlement environment be placed alongside a current, machine-readable hydrologic network crosswalk for the fixed N05_E18 anchor without treating them as the same measurement?

This run follows the SOP's two-sided procedure. The historical end uses Internet Archive material for a dated 1820 observation. The modern end uses current USGS NWIS and National Hydrography Dataset Index (NLDI) responses. The result is a geography-and-network bridge, not a time-series reconstruction.

## Spatial and evidence boundary

The fixed cell is much larger than the Merrillville anchor and includes mixed land, lake, wetland, river, urban, industrial, and suburban settings. The Archive.org source describes Chicago and nearby routes rather than the whole cell. The USGS station and NLDI responses describe points, reaches, catchments, or linked monitoring sites rather than the whole cell. No observation below should be generalized to a cell-wide value without a separate aggregation rule and additional sampling.

## Raw observations — historical end

### 1. 1820 Chicago-area settlement and waterway conditions

- **Date:** August 29, 1820, as reproduced in the source's account of Henry Schoolcraft's journey.
- **Source-reported observation:** The party reached Chicago, found four or five resident families, and described the nearby Potawatomi population as holding the site as a center of trade. The account identifies Fort Dearborn and reports that the Chicago River was ample and deep for several miles but obstructed near Lake Michigan by lake sand; the banks are described as black, sandy, fertile soil.
- **Geographic scope:** Chicago village, Fort Dearborn, and the adjacent river/lake interface. Chicago lies west of the N05_E18 western boundary in the fixed grid, so this is a connected-route observation, not an in-cell population or water measurement.
- **Source type:** compiled historical volume reproducing an 1820 travel account; qualitative observation, not a modern measurement.
- **Page provenance:** printed page 189; PDF page 201 of 706 in the downloaded scan. The preceding expedition description is on printed page 188 / PDF page 198.
- **Source:** J. R. H. / Chicago Antiquities, *Chicago Antiquities*, Internet Archive item `chicagoantiquiti00hurl`, OCR and scan.
- **URL:** https://archive.org/details/chicagoantiquiti00hurl
- **Scan URL:** https://archive.org/download/chicagoantiquiti00hurl/chicagoantiquiti00hurl.pdf
- **Extraction:** OCR located the passage; scan checked on PDF page 201.
- **Confidence:** medium for the dated route and settlement description; low-to-medium for exact wording and quantitative implications because the volume is a later compilation and the account uses settler-era ethnographic language.

The source also preserves the report's characterization of the Potawatomi as the local "lords of the soil." That wording is retained here only as evidence of the source's framing, not as a neutral description. The passage is settler-centered and should not substitute for Indigenous-authored or community-controlled historical evidence.

### 2. Current hydrologic network crosswalk at the Merrillville anchor

- **Request:** USGS NLDI `hydrolocation` for `POINT(-87.3327 41.4828)`.
- **Raw response:** The provided anchor point was associated with an automatically indexed hydrologic location at longitude `-87.33393740603242`, latitude `41.48243980835267`, reach code `04040001000480`, COMID `3399712`, and NLDI measure `10.873528411319496`. The response also preserved the original provided point as a separate feature.
- **Interpretation boundary:** This is a current network-index match near the anchor, not proof that the same channel, route, or settlement function existed in 1820.
- **Source:** USGS NLDI API, retrieved 2026-08-09.
- **URL:** https://api.water.usgs.gov/nldi/linked-data/hydrolocation?coords=POINT(-87.3327%2041.4828)
- **Value type:** machine-readable current network crosswalk.
- **Confidence:** high for the returned API response and coordinate association; medium for using it as a cell-representative observation because it is one anchor point.

A network navigation request from COMID `3399712` returned nearby NWIS-linked features within the requested 25-unit search:

| Identifier | Source-reported name | Coordinates | Reach code | NLDI measure |
|---|---|---:|---|---:|
| `USGS-413402087151801` / `IN033-413402087151801` | Deep R, 1680 ft US of Lake Park Ave at East Gary, IN | 41.5672222, -87.2550000 | `04040001000025` | 79.4708 |
| `USGS-04092990` | Lake George at Hobart, IN | 41.53475918, -87.2583688 | `04040001001263` | 0.0 |
| `USGS-04092975` | Turkey Creek at SR 53 at Merrillville, IN | 41.5044722, -87.33588889 | `04040001000478` | 56.0739 |
| `USGS-04093000` | Deep River at Lake George outlet at Hobart, IN | 41.53614807, -87.25697989 | `04040001000029` | 43.522 |
| `USGS-04092977` | Turkey Creek at 61st Ave at Merrillville, IN | 41.50744444, -87.32375 | `04040001000474` | 82.632 |

The table reports returned network metadata only. The `0.0` NLDI measure for Lake George is a network-position value, not a water quantity and must not be treated as a zero observation.

- **Network request URL:** https://api.water.usgs.gov/nldi/linked-data/comid/3399712/navigation/DM/nwissite?distance=25
- **Confidence:** high for identifiers, names, coordinates, reach codes, and returned measures; medium for spatial interpretation because NLDI navigation semantics and the requested distance are network-specific.

### 3. Current NWIS station metadata for a nearby in-cell site

- **Station:** `USGS-04092977`, Turkey Creek at 61st Avenue at Merrillville, Indiana.
- **Coordinates:** 41.50744444° N, -87.32375° W.
- **Station type:** surface-water site (`ST`).
- **Datum and positional metadata:** NAD83 coordinates; coordinate method `G`; coordinate accuracy code `1`; NAVD88 altitude `598.27` with stated accuracy `0.08`.
- **Hydrologic metadata:** HUC `04040001`; drainage area `36.4` square miles; Eastern time zone; NWIS reliability and groundwater flags as returned by the RDB response.
- **Date fields:** `construction_dt` and `inventory_dt` were blank in this response. Blank metadata is preserved as missing, not interpreted as no construction or no inventory.
- **Source:** USGS NWIS site service, expanded RDB response retrieved 2026-08-09.
- **URL:** https://waterservices.usgs.gov/nwis/site/?format=rdb&sites=04092977&siteOutput=expanded
- **Value type:** authoritative machine-readable station metadata; no hydrologic measurement extracted in this run.
- **Confidence:** high for the returned station fields; medium for representing the full cell because this is one monitoring point.

## Source interpretation

The historical source supports a bounded interpretation that the Chicago-area route combined a lake-edge settlement, a shallow or obstructed river-to-lake interface, and Indigenous-controlled trade context in 1820. The modern sources support a separate observation that the Merrillville anchor sits within a currently indexed network of Turkey Creek, Deep River, Lake George, and nearby monitoring features. Together, they justify a **route-and-network continuity hypothesis**: the pilot cell remains connected to the broader Lake Michigan–Calumet–Kankakee/Great Lakes system through water and transport corridors.

That hypothesis is not a claim that the 1820 Chicago River condition, the Potawatomi trade system, and the present Turkey Creek/Deep River network are one continuous measured system. The historical and modern footprints differ, and the modern API does not provide historical continuity. The connection is therefore classified as **related but not equivalent** under the SOP variable crosswalk.

## Derived layer

No derived constraint, adaptive-capacity value, energy total, population total, or water-quality score was calculated.

The only transparent relationship identified in this run is a qualitative bridge:

```text
1820 historical route/settlement observation
        + current NLDI/NWIS network crosswalk
        -> candidate geography/network continuity hypothesis
```

This is not a numerical formula and cannot support a quadrant assignment.

## Model classification

- `provisional_quadrant`: `unresolved`
- **Reason:** the evidence is point- and route-specific, historical and modern measures are not directly equivalent, the fixed cell is mixed and larger than the source footprints, and the required raw tables for constraints and adaptive capacity are incomplete.
- **Alternative explanations:** modern network connectivity may reflect engineered drainage, urban development, and monitoring-site selection rather than persistence of a historical route; the 1820 account may reflect a traveler/compiler's selective observation; Chicago-route evidence may not represent the Merrillville portion of the cell.

## Missingness and uncertainty

- `geographic_match_uncertain`: the 1820 source is centered on Chicago and the modern crosswalk is centered on Merrillville; the route between them is not mapped here at a common historical and modern resolution.
- `period_match_uncertain`: 1820 and 2026 are anchor observations, not a continuous time series.
- `historical_measure_not_available`: no comparable 1820 flow, stage, discharge, water-quality, population, or trade-volume measurement was extracted.
- `source_exists_not_accessible`: National Archives treaty object pages remain difficult to extract programmatically in this environment; this note does not treat catalog or API absence as treaty-text absence.
- `historical_source_bias`: the Archive.org volume is a later, settler-centered compilation and includes derogatory ethnographic framing.
- `historical_measure_not_available`: no Indigenous-authored or community-controlled source was located in this bounded run.
- `not_applicable`: no sector-wide numerical aggregation was attempted.

No missing or blank field has been converted to zero. In particular, the NLDI `measure: 0.0` for Lake George is a network position, and blank NWIS construction/inventory dates are missing metadata.

## Next search path

1. Retrieve a primary or digitized treaty/map object for the 1821, 1832, 1833, and 1836 Potawatomi-related records and map their clauses or cession boundaries against the fixed N05_E18 cell and neighboring octagon cells.
2. Crosswalk the 1820 Chicago/Calumet route to historical maps and later municipal or engineering surveys with page- or map-level provenance.
3. Use USGS NLDI navigation and NWIS site metadata for the remaining Great Lakes pilot anchors, keeping reach, catchment, station, and cell scopes separate.
4. Locate Indigenous-authored, tribal-government, or community-controlled historical and contemporary sources before interpreting the route continuity hypothesis as institutional or cultural evidence.
5. Build the 1950–2000 overlap from comparable water, population, transport, and industrial records before any formula lock.

## Provenance register

| Evidence | Tier | Identifier / version | Date accessed | URL |
|---|---|---|---|---|
| Historical compiled volume and 1820 Schoolcraft passage | C (digitized historical source; secondary compilation) | Internet Archive `chicagoantiquiti00hurl`, printed pp. 188–189, PDF pp. 198 and 201 | 2026-08-09 | https://archive.org/details/chicagoantiquiti00hurl |
| Historical scan used for page verification | C | `chicagoantiquiti00hurl.pdf`, PDF pp. 198 and 201 of 706 | 2026-08-09 | https://archive.org/download/chicagoantiquiti00hurl/chicagoantiquiti00hurl.pdf |
| Anchor-to-reach hydrolocation | A | USGS NLDI API response, COMID `3399712`, reach `04040001000480` | 2026-08-09 | https://api.water.usgs.gov/nldi/linked-data/hydrolocation?coords=POINT(-87.3327%2041.4828) |
| Nearby linked NWIS features | A | USGS NLDI navigation response from COMID `3399712`, distance `25` | 2026-08-09 | https://api.water.usgs.gov/nldi/linked-data/comid/3399712/navigation/DM/nwissite?distance=25 |
| Turkey Creek station metadata | A | USGS NWIS expanded RDB, station `04092977` | 2026-08-09 | https://waterservices.usgs.gov/nwis/site/?format=rdb&sites=04092977&siteOutput=expanded |

## Bottom line

This run adds one defensible, bounded bridge: a page-verified 1820 Chicago-area route and settlement observation can be placed beside a current USGS NLDI/NWIS network crosswalk centered on Merrillville, but the sources remain related rather than equivalent. The note strengthens the pilot's geography/network evidence while leaving the sector score and `provisional_quadrant` unresolved.