8. The Future of Coordinates
Chapter 2 explained why a coordinate can change over time even when nothing physically moved. What comes next is the answer the National Geodetic Survey, NGS, the federal agency responsible for the country's official reference frames and datums, is actually building: reference frames designed around that motion from the start, instead of treating it as an inconvenience to work around after the fact.
Why NAD83 Is Being Replaced
NAD83 gave surveyors, engineers, agencies, and mapping software a shared horizontal reference for decades. Its origin doesn't sit exactly at the Earth's modern center of mass, though, and its relationship to current global GNSS frames isn't perfectly aligned. That gap is invisible for ordinary navigation and matters considerably once centimeter-level agreement between receivers, correction networks, and international data is actually expected.
Why NAVD88 Is Being Replaced
NAVD88, the familiar vertical datum behind most US elevations, was built primarily from spirit leveling tied to a single benchmark in Canada. Over long distances, leveling error accumulates, and some of the original benchmarks have since moved, subsided, or been destroyed entirely. Maintaining a nationwide vertical network through physical marks alone has become genuinely difficult.
GNSS offers a different path. A receiver can measure ellipsoid height almost anywhere with a clear view of the sky, and a high-quality geoid model can then convert that into a gravity-related orthometric height. The future vertical system depends far less on finding a nearby benchmark and far more on combining GNSS directly with a national gravity model.
Four Reference Frames Instead of One
The modernized National Spatial Reference System won't use a single plate-fixed frame for the whole country. It will use four, one for each major tectonic plate involved: NATRF2022 for North America, PATRF2022 for the Pacific, CATRF2022 for the Caribbean, and MATRF2022 for the Mariana plate.
A tectonic plate is not a perfectly rigid sheet, and plate-fixed does not mean motion-free. Earthquakes produce sudden movement, sediment compacts, and former ice sheets keep affecting the crust long after the ice itself is gone. The modernized system includes deformation models specifically to describe motion a plate's broad rotation alone can't explain, treating motion as something worth describing rather than a nuisance to hide.
A Coordinate With a Fourth Dimension
A traditional coordinate is usually written as latitude, longitude, and height. A modern high-accuracy coordinate needs a fourth value alongside those three: the epoch, telling anyone reading it exactly when that coordinate describes the point. Without it, a high-precision coordinate can be incomplete even when every single digit was copied correctly.
NAD83(2011) already has its own reference epoch, 2010.00, so an epoch attached to a coordinate isn't new. What's actually changing is how that epoch gets treated. The current system defines one reference epoch and largely leaves it there for years at a time. NGS has committed to publishing updated reference epochs for the modernized system on a standing five-year cycle instead, making epoch tracking a routine, ongoing part of how the system operates, rather than a single date set once at the start and left alone.
A New Vertical Datum
The North American-Pacific Geopotential Datum of 2022, NAPGD2022, will replace NAVD88 and the other vertical datums currently in use across US regions and territories. It's broader than a simple list of benchmark elevations, a gravity-based system built to provide mutually consistent orthometric heights, geoid undulations, gravity values, and other physical quantities tied to Earth's actual gravity field.
Its most visible product for ordinary GNSS users will be GEOID2022, converting ellipsoid height in the new terrestrial reference frames into orthometric height under NAPGD2022, the same underlying relationship the geoid already represents, just kept current as gravity and the geoid's own shape shift over time as water and ice redistribute mass. For most everyday projects those changes are tiny. The value of building in that time-dependence is that it's there when a project's accuracy and duration actually need it.
A familiar existing US workflow runs from a GNSS observation through NAD83(2011) coordinates, through GEOID18, into NAVD88 orthometric height. The modernized version runs from a GNSS observation at a stated epoch, through NATRF2022 or one of its sibling frames, through GEOID2022, into NAPGD2022 orthometric height. The exact software steps will vary by vendor and platform. What has to travel together, in either version, is the horizontal frame, the vertical datum, the geoid model, and the epoch, all at once.
The Numbers Will Genuinely Shift
Moving a project from NAD83 and NAVD88 to the modernized system changes the coordinate values themselves. The reference surfaces and frames used to describe it do.
Early estimates from national mapping agencies put the immediate horizontal shift somewhere between roughly 0.7 and 2.5 meters in some regions, since the new frames align more closely with modern, global, Earth-centered frames than NAD83 ever did, with vertical shifts of a comparable scale possible too, since NAPGD2022 rests on a new gravimetric geoid rather than the historical leveling network that originally defined NAVD88.
A project's coordinates shift by more than a meter the moment it switches from the legacy system to the modernized one. Does that mean the old survey was wrong, or the new one is? Neither. It means two different, both valid, reference systems are describing the same physical point, and the shift should be handled through a documented transformation and clear metadata, never by quietly editing digits until old and new numbers happen to match.
What Actually Changes for a SparkPNT User
Most receiver hardware keeps doing exactly what it already does: measuring GNSS signals and solving positions. The bigger changes show up in correction services, firmware, field applications, GIS software, transformation tools, and project specifications. Expect new choices for reference frame and realization, coordinate or observation epoch, GEOID2022 in place of GEOID18, NAPGD2022 in place of NAVD88, and a substantially expanded State Plane Coordinate System of 2022, adding new low-distortion projection options alongside the traditional statewide zones.
A receiver will still display latitude, longitude, and elevation. The difference is that those values will carry more explicit meaning behind them than before.
What's Worth Preserving Either Way
The safest, future-proof habit is saving a coordinate together with everything needed to reproduce it: observation date and time, reference frame and realization, coordinate or reference epoch, ellipsoid height, orthometric height where used, geoid model, vertical datum, map projection and units, correction source or base station, and antenna model with its measured height. A file containing only latitude, longitude, and elevation can look perfectly complete today and turn genuinely ambiguous later. Metadata is what keeps precision from quietly expiring.
Don't Panic Over the Year in the Name
NATRF2022, NAPGD2022, and GEOID2022 all refer to one coordinated family of modernized products, and that number in the name doesn't mean every piece was placed into official service during calendar year 2022. As of this writing, official adoption is targeted for late 2026, with components still being tested on NGS's own beta platform. The practical question was never the year in the name. It's whether a specific project, correction service, software package, or agency has actually adopted the modernized system yet, and which specific version it supports.
Large coordinate-system changes never happen everywhere on one single morning. Agencies update specifications on their own schedules. States publish new projection zones as they're ready. Software vendors add support incrementally. Correction providers revise their own reference frames independently. During that whole transition, a single receiver may be capable of producing coordinates in several frames at once, two project files can easily use two different systems, and a transformation may be required before the two can be combined safely at all. The answer was never memorizing every acronym. It's asking the same questions this entire series has built from the start: relative to what, when, height above what, and how was it corrected.
The Story This Series Has Followed
This series has followed one idea through eight chapters:
- A coordinate is more than three numbers.
- The Earth never stops moving.
- A precise coordinate needs a date.
- Every coordinate is relative to a reference frame.
- RTK solves a measurement problem precisely, but a FIX alone doesn't confirm the reference frame, epoch, or base coordinate behind it.
- GNSS height and practical elevation rely on two different reference surfaces.
- The displayed coordinate is the end of an entire processing chain.
- The coordinate systems replacing today's build deformation modeling, beyond simple plate rotation, directly into the frame, and treat the reference epoch as something to republish routinely rather than define once and leave static.
Once those ideas are actually understood, the acronyms stop being obstacles and become exactly what they were always meant to be: labels.
The companion series that follows applies every one of these ideas directly to the questions that actually show up at the workbench and in the field, starting with one of the most common surprises in precision GNSS: a receiver that is horizontally correct in every way, while still appearing to report the wrong elevation entirely.