Parcel Data

I built my own whole API from scratch to display parcel and other data in realtime as you browse a map. My challenge was to develop a high-performance system that could retrieve data as fast as you can browse the map, without ever clicking on anything... just move the map and watch what happens.

This was a fun software challenge for me and (AFAIK) nobody else has anything like this, but since I've never looked, I could be wrong. I also really enjoy working with databases (which is why I'm writing another one from scratch right now) and we're talking about BIG datasets when you work with parcels. My app only covers Southern New Jersey (Southeast PA has some other data, but not parcels). It's ~4,000 square miles - half of one of the smaller states - and even so, the database contains about 1.4 million parcels! Add the fact that my map also contains full building footprints, also more than a million features in the same small map.

All of this is a good example for why I gave up making maps for Garmin, they just can't handle this level of density. Towards the end of my "Garmin period" I made a mid atlantic map with full buildings, including New York City, Philadelphia, etc. So, millions of buildings. I was surprised when this worked very smoothly in Basecamp - and even more surprised when it also worked well in Mapsource. Then I sent it to several GPS'es to test and boom! They all just choked on that amount of extreme detail.

I think that onX used to make Garmin versions of their maps but IIRC they discontinued them and now only have their own app. I don't see how Garmin devices could work acceptably with this density of data in a small geographic area. Those are probably more like the number of features in a whole map of the US on Garmin!

Anyway, my app is a bit of a "proof of concept" to show what can be done in a smaller geographic area. Would like to expand it, but "so many maps, so little time:

The parcel data itself is fascinating, a real can-of-worms once you start digging in. In my 1.4 million record dataset, over 300,000 records are "orphans" - the geometry of the parcel is there, but there's no matching tax record. I set out to understand that and try to improve things and it was pretty interesting. The main problem is that when somebody purchases a bunch of parcels at the same time, they only put the owner into into one of the parcels. Then they add a note which lists the other parcels which are part of the group. But there is no formal way to record that in the database, such that you could identify the other parcels. It's just a note, written however somebody felt like describing it! I found a state document about their database that had rules for how you should enter that data in an attempt to standardize things, but it didn't seem to help.

So I used various techniques to reunite some of the "orphans" with their "parents" Was really only interested in openspace parcels, or land adjacent to public openspace, but I managed to reunite about 20% of the "broken families" before I gave up!

And New Jersey made things harder recently, as the result of that horrible incident where a family member(s?) of a judge were stalked and killed (all over the news a few years ago). They passed a law that gave certain public employees the right to have their names removed from databases within 90 days of requesting (or something like that). As a result, the state simply redacted ALL the owner names from the parcel datasets since that was simpler than trying to only remove what was required.

I had a copy of the old dataset, from just before that law. So I went through it and redacted all the private owners' names but left the names of property owned by companies and public agencies. That makes my dataset more useful than the "official" one while still preserving privacy for individual owners.

I did a trial subscription for onX and it looked pretty good, if you need that kind of thing. I know some hunters who love it. I cancelled the subscription before the trial ended and even deleted my onX account, but they sent me spam every few days for two or three years after that, LOL. So be prepared for that if you sign up for a free trial. No big deal, it all went into the spam folder, but they were very persistent!

Garmin advertises some kind of mapping with parcel data.... is it called HuntView, I think? Don't know anything about that myself. But, if you're interested, this is my own app

https://boydsmaps.com/pines/#14/39.666166/-74.732833/darkstr...

You can choose a variety of maps on the menu, this one has aerial imagery with parcel boundaries

https://boydsmaps.com/pines/#15/39.666166/-74.732833/parcels...

The first map - with parcel boundaries, roads, towns and other features - still only covers the Pine Barrens, but I've been working on a much larger mid-Atlantic US version that covers several states. When I first built this parcel app, I really couldn't find much data outside of NJ. But more recently, other states have started publishing. I downloaded as much as I could find a couple years ago and did a lot of work on the big map, but still haven't finished it, and that could take awhile. But hopefully will be available sometime next year. That won't be "wired up" to my parcel software, but it will show property lines and the public openspace will be shaded green, so it should still be helpful....

I go back a ways with OnX. In fact, I bought a micro SD card from them with OnX for Minnesota. That, of course, worked with my Garmin, but they have discontinued maps on micro SD and now have the Android and Apple apps.

I do currently have a subscription from them for OnX Offroad. I bought it during one of their holiday sales this summer for 70% off, so $10.50 for a year of their Premium plan. Since I have T-Satellite and this is one of the apps that works with it, I wanted to see how well it worked on T-Satellite. It does work with T-Satellite, but not as well as when it has terrestrial data.

The specific Garmin devices that support parcel data include:

Smartwatches
These premium smartwatches support the Garmin Outdoor Maps+ subscription, which downloads state plat maps, private parcel boundaries, and landowner information directly over Wi-Fi:

fēnix Series: fēnix 7 series, fēnix 8 series, and fēnix 8 Pro

Epix Series: epix (Gen 2) and epix Pro Gen 2 series

Enduro Series: Enduro 2 and Enduro 3

tactix Series: tactix 7 series

MARQ Series: MARQ (Gen 2) series

Handheld GPS Devices
These standalone outdoor handhelds can run either Outdoor Maps+ or load Garmin HuntView Plus microSD cards/digital downloads:

GPSMAP Series: GPSMAP 67, 67i, 66 series (66s, 66st, 66i, 66sr), and GPSMAP 276Cx

Montana Series: Montana 700, 700i, and 750i

Alpha Series: Alpha 200, 200i, 300, and 300i (often paired with the Alpha tracking app)

Oregon Series: Oregon 700 and 750 series (via legacy HuntView Plus compatibility)

All-Terrain Motorized Navigators
The Garmin Tread Series (including Tread, Tread - Base Edition, Tread Overland, Tread XL, and Tread Textron) comes with a native Private Parcels map layer preloaded onto the device. This layer shows boundaries for land plots of 4 acres and larger without requiring an extra subscription.

Note: Garmin devices use consumer-grade GPS receivers, meaning parcel boundaries are meant for a general overview and are not legally binding for official land surveying.

The Polaris Ride Command app has Parcel Data that they refer to as Landowner/County Lines. I don't know how often it is updated or how it compares to CalTopo or Regrid. Regrid limits the number of requests to 25 per day on their free account.

While it seemed hard for me to find 4 or 5 years ago, now I see more states making parcel data available for download. Some states may offer more complete data than others, I downloaded all I could find for the Northeast US a couple years ago, and it was maybe as much as 50% coverage of that region (~10 states). But these datasets get so huge, I was stripping out all the details because I only wanted the property lines.

These can be combined with openspace data to show boundaries of public land, which is what I'm doing on these new maps, not displaying detailed parcel data like my special app. Anyway, you could use an open source app like QGIS to make maps from all of this stuff yourself. There's a learning curve for sure, depending on exactly what you are trying to do. Making Garmin traditional .img files is certainly possible, but lots of issues there.

I don't know, unless you're like me and really just enjoy making maps, if you need parcel data for some reason then purchasing from Garmin or using onX probably makes the most sense. Neither of those options would get me very interested.

There have been some Garmin format maps of property ownership posted at GPSFileDepot over the years. Never looked at them myself, but think they are probably still there (also some other commercial products that start to just look like spam to me also...)