DeedMapper Web App

A web application for viewing historical land records from DeedMapper (.mbl files) with optional overlay on USGS topo maps.

Files

• deed-mapper-app.html - The main web application
• NC_Iredell.mbl - Database of historical land surveys example: (Iredell County, NC area), other .mbl files can be loaded

How to Use

1. Open deed-mapper-app.html in a web browser (Chrome recommended)
2. Click "Choose File" and select your .mbl database file
3. Plots will display on the canvas with the deeds table on the right

Features

• Plot Display: Shows land survey boundaries with metes and bounds
• Interactive Table: Click rows to highlight and center on plots
• Search: Filter table by ID, name, date, etc.
• Sortable Columns: Click column headers to sort
• View Modal: Click "View" link for detailed single-plot view
• Type Filtering: Show/hide Surveys, Deeds, or Other record types
• Customizable Labels: Choose which fields appear in plot labels
• Geographic Mode: Overlay plots on USGS topo maps

Key Settings

Scale Multiplier: 0.6

Controls the size of individual plot shapes. This value correctly scales metes and bounds measurements (poles, chains) for display.

Geographic Mode Settings

Some of these can probably be removed at some point since I am now icluding the values in a comment in the .mbl file

Setting	Value	Description
Anchor Plot ID	Rowan-3090	Reference plot for positioning
Anchor Lat	35/55/25	Latitude in dd/mm/ss format
Anchor Lon	-80/49/27	Longitude in dd/mm/ss format
Geo Scale	1.667	Converts MBL units to feet (= 1/0.6)
Rotation	7	Degrees clockwise for magnetic declination correction

Why These Values?

• Geo Scale = 1.667: Mathematically derived as 1 / Scale Multiplier. The MBL loc coordinates appear to be in feet.
• Rotation = 7 degrees: Compensates for magnetic declination change from 1780s to present. Original surveys used magnetic north; the topo map uses true north.

Coordinate System Notes

• Metes and Bounds Units:

  • 1 pole (p) = 16.5 feet
  • 1 chain (c) = 66 feet
  • 1 rod (r) = 16.5 feet

• Geographic Conversion (at ~36°N latitude):

  • 1 degree latitude ≈ 364,000 feet
  • 1 degree longitude ≈ 294,000 feet

Adjusting Position on Map

To Move	Adjust
North	Increase latitude (e.g., 35/55/25 → 35/55/35)
South	Decrease latitude (e.g., 35/55/25 → 35/55/15)
East	Decrease longitude magnitude (e.g., -80/49/27 → -80/49/17)
West	Increase longitude magnitude (e.g., -80/49/27 → -80/49/37)

Approximate scale: 1 second ≈ 100 feet (lat) or 80 feet (lon)

Future Improvements to Consider

• Additional basemap options (satellite, street map)
• Export to GeoJSON or KML
• Save/load settings
• Print-friendly layout
• Neighbor relationship visualization

Technical Details

• Built with Leaflet.js for mapping
• USGS National Map topo tiles for basemap
• Single-file HTML application (no server required)
• Works offline except for topo map tiles

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Created with Claude Code, February 2025