# N05_E18 Great Lakes pilot: 1996–2019 Lake County plat-book crosswalk **Research date:** 2026-08-10 UTC **Sector:** `N05_E18` — canonical 24 × 24 grid cell, 37.5–45.0° N and 270–285° E (90–75° W) **Anchor:** Merrillville, Indiana, approximately 41.4828° N, 87.3327° W **Time band:** `1950-present` contemporary/late-industrial transition, with 1996 and 2019 archival map anchors **Status:** bounded historical/modern map-source crosswalk; no derived score and no `provisional_quadrant` ## Selection and research boundary The preceding N05_E18 notes identified a remaining local map gap: the 1907 Allen County atlas was inspected, but the Merrillville/Gary/Hobart anchor lies in Lake County, and the fixed-cell historical map record for the corridor was not yet documented. This run searched Internet Archive’s machine-readable catalog and inspected the available OCR for Lake County plat-book objects. It selected the 1996 and 2019 Lake County plat books because they provide item-level Archive.org records, page-derived OCR, township/range map context, watershed material, and a direct local bridge to the Merrillville anchor. These books are landownership and planning/map publications, not equivalent to a cadastral database, a legal title record, a hydrologic dataset, or a complete historical record. Their observations are retained at the source footprint and date. No parcel area, infrastructure capacity, watershed area, population, or cell-wide score is derived. ## Spatial and evidence boundary The 2019 book’s OCR contains a `Hobart Townships 35N & 36N - Ranges 7W & 8W` map section, a `Key Map of Lake County, Indiana`, and a `WATERSHEDS MAP`. It also contains township/range and named-feature references for the Calumet–Hobart–Gary corridor. The 1996 OCR contains a county book with a highway-map/township-map structure, a watershed-related section, and an index that includes Merrillville, Gary, Gary City Airport, Gary Water Works, Gary Steel Products Corp., and pipeline/engineering firms. The Merrillville anchor is geographically represented by the source collection’s Lake County coverage, but the OCR alone does not supply a georeferenced polygon for the fixed `N05_E18` cell. The source pages were not converted into GIS geometry in this run. ## Raw observations ### A. 2019 Archive.org item and catalog metadata - **Item:** *Plat Book Lake County, Indiana (2019)*. - **Creator:** Lake County Soil & Water Conservation District. - **Publication metadata:** the Archive.org item records the date as `2019`; the item description identifies Mapping Solutions GIS as publisher for the Lake County Soil & Water Conservation District. - **Item identifier:** `plat-book-lake-county-indiana-2019-images`. - **Derivatives:** PDF, OCR text (`Plat BookLakeCountyIndiana2019_images_djvu.txt`), OCR XML, page-number JSON, scan data, and JP2 image archive are exposed in the item metadata. - **OCR contents:** the item’s table-of-contents text includes a key map, map legend, land descriptions, aerial and landownership maps, townships, county road map, soils map, watersheds map, road index, landownership index, initialed-parcel index, and business directory. - **Evidence type:** digitized landownership/map publication with item-level metadata and machine-readable OCR; OCR is a locator and transcription aid, not a substitute for visual map inspection. ### B. 2019 township/range and named-feature observations - The OCR identifies a map section titled `Hobart Townships 35N & 36N - Ranges 7W & 8W`. - The same map context includes `Hobart`, `Merrillville`, `Gary`, roads including `Grand Blvd`, `Randolph St`, `Colorado St`, and references to `Lake Michigan` and the Indiana Dunes National Park area in the broader county map material. - The OCR identifies a `Key Map of Lake County, Indiana` whose legend includes incorporated city/town/village, cemetery, church, park, interstate/federal/state/county highways, county roads, city streets, railroad, watershed boundary, and river/creek symbols. It states a map scale of `1 Inch = 0.84 Miles`, identifies 2018 USDA National Agriculture Imagery Program (NAIP) imagery, and says the book uses elevation data derived from the USGS National Elevation Dataset (NED). - These are source statements and map-label observations. They do not establish that every listed feature intersects `N05_E18`, nor do they establish feature length, area, capacity, or continuity. ### C. 2019 watershed-map observations - The OCR identifies a `WATERSHEDS MAP` covering Lake County and neighboring counties/states, including Lake Michigan, Cook County and Will County, Illinois, Porter County, Jasper County, Newton County, and Kankakee River-related labels. - The legend text states that identified watersheds are classified by the USGS as HUC-10, described in the book as fifth-level watersheds typically sized 62–390 square miles. This is the book’s explanatory text; it is not an independently recomputed HUC area measurement. - The source’s watershed map is relevant to a hydrologic crosswalk, but its printed regional footprint and map projection were not transformed into the fixed 24 × 24 cell. No watershed share or overlap percentage is assigned. ### D. 1996 Archive.org item and catalog/OCR observations - **Item:** *Plat Book Lake County, Indiana (1996)*. - **Creator:** Lake County Soil & Water Conservation District. - **Publication metadata:** the Archive.org item records the date as `1996`; the description identifies a county highway map, diagram of townships, legend for township maps, section analysis, city street maps, and township maps. The item metadata identifies Athentic Inc. as publisher for the Lake County Soil & Water Conservation District. - **Item identifier:** `plat-book-lake-county-indiana-1996-images`. - **Derivatives:** PDF, OCR text (`PlatBookLakeCountyIndiana1996_images_djvu.txt`), OCR XML, page-number JSON, scan data, and JP2 image archive are exposed in the item metadata. - **OCR index observations:** the item’s OCR includes entries for Merrillville, Gary, Gary City Airport, Gary Water Works, Gary Steel Products Corp., and a pipeline company. It also contains engineering/surveying and land-planning references located in Merrillville. These are index or advertisement observations, not independently verified facility records or operating measurements. - **Book explanation:** a section-analysis passage states `A rod is 16 1/2 feet`, `A chain is 66 feet`, and `A mile is 5280 feet`. These are preserved as printed unit statements; they are not used for a new conversion or score. ## Source interpretation 1. The two items add a direct local map-source path for the Lake County portion of the Great Lakes pilot, including the Merrillville/Gary/Hobart corridor that the Allen County 1907 atlas could not represent directly. 2. The 2019 item provides a documented map legend, township/range map context, watershed-map context, and declared source inputs (2018 NAIP and USGS NED-derived elevation). This strengthens provenance for a future spatial crosswalk but does not itself provide machine-readable layers or a fixed-cell measure. 3. The 1996 item provides an earlier local landownership/map and index context. Its named-property and business-directory entries are evidence that those labels occur in the publication, not proof of ownership, operation, production, emissions, or infrastructure capacity. 4. The source footprints are administrative and publication-specific. They do not equal the canonical `N05_E18` geometry, and no overlap or continuity is inferred from proximity. 5. The 1996 and 2019 editions are not treated as a continuous time series. Differences in publication purpose, map construction, feature coverage, and OCR quality remain unresolved. ## Geography and variable crosswalk | Source observation | Modern/canonical target | Relation | Limitation | |---|---|---|---| | 2019 Lake County key map and township/range maps | Fixed `N05_E18` geometry | related, not equivalent | Printed county/map footprints were not georeferenced or clipped | | 2019 watershed map and HUC-10 explanatory text | USGS watershed layers and NLDI reaches | related, not equivalent | Source map was not digitized; no overlap, area, or reach identity derived | | 2018 NAIP and USGS NED-derived inputs stated in 2019 book | Current raster/elevation products | source lineage only | The underlying rasters were not retrieved or measured here | | 1996 index entries for Gary Water Works, Gary Steel Products Corp., and pipeline/engineering firms | Infrastructure and industrial records | named-feature lead | Index/advertisement text does not establish capacity, dates, status, or cell-wide totals | | 2019 roads, railroads, rivers/creeks, and township/range labels | Current transport/hydrologic networks | related, not equivalent | Labels do not establish route length, operational continuity, or modern network identity | ## Derived layer No numerical sector score was derived. No parcel count, land-use percentage, watershed area, route length, facility capacity, energy value, population value, constraint score, adaptive-capacity indicator, or formula output was calculated. The bounded evidence-chain update is: ```text 1996 Lake County plat-book item + OCR/index context + 2019 Lake County plat-book item + map/watershed context + existing N05_E18 modern USGS/WQP/Census records -> stronger local source path for map and feature crosswalk while fixed-cell geometry, source-layer extraction, and comparable measures remain unresolved ``` This is a source-coverage result, not a measurement or model score. ## Model classification - `provisional_quadrant`: `unresolved` - **Reason:** the books are map/publication sources rather than cell-wide machine-readable measurements; the relevant pages were located through OCR but not fully digitized/georeferenced; the 1996/2019 footprints are not a continuous time series; and the Great Lakes pilot’s comparable tables remain incomplete. - **Model boundary:** `provisional_quadrant` is a model output and is not an archival fact. ## Missingness and uncertainty - `page_image_extraction_incomplete`: relevant OCR sections were located, but a complete page/image audit of the Lake County township, key, road, and watershed plates was not completed in this run. - `ocr_locator_only`: OCR may misread labels, units, and page boundaries; principal claims should be checked against rendered page images before use as raw map observations. - `fixed_cell_geometry_unresolved`: no polygon or overlap calculation was created for `N05_E18`. - `source_layer_unretrieved`: the NAIP, NED, and any underlying GIS layers named by the 2019 book were not retrieved from their original custodians. - `historical_continuity_unresolved`: 1996 and 2019 editions are dated anchors, not a continuous record of land ownership, industry, water, or transport. - `facility_status_unresolved`: index and advertisement entries do not establish operating dates, capacity, emissions, ownership, or current status. - `watershed_overlap_unresolved`: no HUC-10 or NLDI intersection with the fixed cell was calculated in this run. - `not_applicable`: no score or quadrant formula was attempted. No archival silence, OCR omission, inaccessible derivative, or publication index entry has been converted into zero. ## Next search path 1. Retrieve the 2019 JP2/PDF pages corresponding to the key map, Hobart/Merrillville township maps, county road map, and watershed map; visually inspect and record page/image identifiers. 2. Retrieve the 1996 pages corresponding to the county highway/township maps and the index entries used here; distinguish map labels from advertisements and directory text. 3. Obtain authoritative USGS HUC-10/NHDPlus/NLDI geometries and intersect them with the fixed `N05_E18` polygon before deriving any watershed or connectivity variable. 4. Retrieve the underlying 2018 NAIP and USGS NED products named by the 2019 book only if their coverage, licensing, and cell-level measurement method can be documented. 5. Continue the separate primary administrative-record search for Gary Works, Gary Water Works, pipelines, permits, and remediation; do not treat plat-book names as operational measurements. 6. Complete the Great Lakes nine-sector comparable raw-observation tables before assigning any quadrant. ## Provenance register | Evidence | Tier | Identifier / page or item scope | Date accessed | URL | |---|---|---|---|---| | 2019 Lake County plat book | C: digitized local map/publication source | Item `plat-book-lake-county-indiana-2019-images`; OCR derivative `Plat BookLakeCountyIndiana2019_images_djvu.txt`; key map, Hobart township section, watershed-map text located by OCR | 2026-08-10 | | | 2019 Archive.org item metadata | C: machine-readable catalog metadata | Creator, date, description, derivative list, page-number and scan-data files | 2026-08-10 | | | 2019 OCR derivative | C: locator/transcription aid | `Plat BookLakeCountyIndiana2019_images_djvu.txt`; named-feature and map-legend passages | 2026-08-10 | | | 1996 Lake County plat book | C: digitized local map/publication source | Item `plat-book-lake-county-indiana-1996-images`; OCR/index context for Merrillville, Gary, water works, steel, and pipeline entries | 2026-08-10 | | | 1996 Archive.org item metadata | C: machine-readable catalog metadata | Creator, date, description, derivative list, page-number and scan-data files | 2026-08-10 | | | Current hydrologic anchor | A: authoritative machine-readable API | NLDI COMID `3399712`; NHDPlus comid source; 27-coordinate reach geometry retrieved during this run | 2026-08-10 | | | Canonical sector definition | A: project record | `N05_E18`, 37.5–45.0° N, 270–285° E; Merrillville anchor; no new values derived | 2026-08-10 | `N05_E18_MERRILLVILLE-sector-record.json` | ## Bottom line This run adds a bounded 1996–2019 Lake County plat-book crosswalk for the Great Lakes pilot. The Archive.org item records and OCR expose a local map-source chain for the Merrillville/Gary/Hobart corridor, including township/range maps, roads, railroads, watershed boundaries, rivers/creeks, named public and industrial properties, and declared 2018 NAIP/USGS NED-derived inputs. The evidence improves source coverage but does not provide a fixed-cell geometry, cell-wide measures, a time series, a derived score, or a defensible `provisional_quadrant`. The next defensible step is page/image inspection followed by an authoritative HUC-10/NHDPlus/NLDI intersection—not a model classification.