Markline: Benchmark Hunting

About Markline: Benchmark Hunting

Markline is the offline field companion for benchmark hunting: finding the brass disks, rods, and survey marks documented by NOAA's National Geodetic Survey.

Explore 793,632 bundled survey marks across the United States and its territories. Search the catalog with no signal and no account. Online maps help you plan where to look.

FIND AND DOCUMENT SURVEY MARKS
• Search by PID or designation, or browse by state and county.
• See nearby marks sorted by distance, with bearings and reported condition.
• Read bundled coordinates, elevation, datum, setting, stability, and recovery history.
• Record found, not found, or destroyed marks with photos and notes.
• Track your progress and export your local recovery log as CSV.
• Open directions in your maps app. Download official NGS datasheets while online and keep them for offline reference.

ACCESS
Try full access for 3 days. After the trial, choose a one-time purchase to unlock continued access. No subscription, no ads, and no Markline account.

PRIVACY
Your recovery log, photos, notes, settings, and downloaded datasheets stay in the app's local storage. Optional online maps use Google Maps. Its SDK automatically processes device and SDK metadata, crash information, IP addresses, and a Maps-specific pseudonymous identifier. Google Play handles purchases; NOAA supplies datasheets when requested.

DATA SOURCE
Survey-mark data comes from NOAA National Geodetic Survey public-domain records. Official source: https://geodesy.noaa.gov/datasheets/index.shtml

Markline is a private reference app. It does not represent a government entity and is not affiliated with, endorsed by, or authorized by NOAA or the National Geodetic Survey.