First, this is cool! Well done.
I live next to a State Park. It sounded really cool when I bought the house. No neighbors! Privacy! There is a trail accessible from my properly that goes into some woods, which you only want to be in during the Fall / Spring because the ticks and chiggers are intense.
The biggest issue with sharing a border with the state is the fence line. Technically it's on them to maintain. The woods are filled with mostly 200 foot trees. They exist right up to my property and fall every year during big storms. There goes the fence line. I have dogs so the fence is important. Otherwise they run out into the woods that have licensed bow-hunting during the Winter.
In practice its impossible to get the fence fixed. You are working through layers of bureaucracy and mismanagement. There is no vested interest from a parks service to work well with hundreds of neighbors individually. I'd build fence lines myself, and could easily pay for it, but it's the upkeep of those fences that would be difficult because so many trees (really, it's every year) fall down from their side.
My main point is that sharing a properly line with the government is more like sharing a properly line with nobody. You may as well own that land. Don't expect any upkeep and go in with eyes open.
This is interesting though not really for me. I know that without trails, I won't be walking past the end of my property onto other property. I've probably spent a year of my life building trails on my own property.
When I look for a parcel of land, I'm also interested in proximity to healthcare, groceries, airports (bad!), motor sports, shooting ranges; general steepness of the property particularly at the roadway (too steep makes the property unusable), topography in general (any flat spots to build a house?); availability of power; water features; bikability (checked by looking at Strava's heatmap); average number of days temperature > 85F; average number of days temperature < 30F. There's more but this list is long enough already.
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If you have public land do you just have people walking over the property boundary onto your parcel all the time? Especially in the more populous states like NJ some of them I'd expect that to be pretty common, interesting idea as a thing that people search out specifically for though.
Regardless, neat site. Couple things, first maybe a disclaimer on why you would want this on the home page? And on the state page itself I can't tell how bordering is different than adjacent. IMO just calling it "within 75m" would be better, and since this is for the US consider making it based on feet :p. Also, I would recommend that at least for user facing strings though you give it a little TLC and remove the really really obvious Claudisms
> official boundary maps, not listing descriptions.
> An analysis of publicly available boundary data — not a survey, and not a listing service
plus everything on the How It Works page is extremely obviously LLM.
Thanks, this is useful feedback.
On people crossing over: it depends a great deal on the land. Next to state game lands you'll see hunters in season; next to a big national forest you may rarely see anyone. It's very dependent on individual perspective and location.
Bordering vs adjacent: bordering means the parcel lines actually touch and there's a measured shared edge; adjacent means no shared edge but within about 250 ft (usually a road or a strip of other land in between). You're right that the state pages don't make that clear, and feet is the better unit for a US site. Tho most US geospatial data is published in metric lol.
And fair point on the copy. I run a small design studio and built this in my free time, I leaned on AI for a lot of the site text. The "Why this exists" section on How it works is my own story, but the rest deserves a pass in my own voice.
> I leaned on AI for a lot of the site text.
So that's why the site text reads as AI slop.
It's weird how people think navigating through undeveloped land is like walking across a parking lot. Brush, branches, thorns, downed trees, uneven ground, etc can make walking through undeveloped land difficult to impossible.
This is cool, but isn't owning property bordering public land undesirable?
Sure, there's the ability to hike directly from your home, but I imagine you'll regularly have people wander on to your property. And if something illegal happens on your property by a different party, you might be liable.
Seems like the cons outweigh the pros. Or is there something I'm missing?
> but I imagine you'll regularly have people wander on to your property
Well, that depends on how large and obvious your property is.
Assuming you have a typical suburban 1/2 acre or 1 acre property, the simplest thing to do is put up a fence, or otherwise make sure that there are no trails that go over the property you use.
Otherwise, you need some kind of bounds marking and obvious "no trespassing" signs.
FWIW: The site identified public lands near my house that have a lot of trails on it. There are trails that go right behind peoples' yards, and most of them either have fences or sheds that make it obvious where the bounds are.
I think for an individual owner there are some downsides, but if you're a big developer buying a large piece of land it can become a selling point. There's a private residential development in my state where they completely enveloped the entrance to an existing state park trail/boardwalk. So to access it, you actually have to go through this gated community. Supposedly anyone can go in if they say they're going to the state park, but I'm not sure that's true in practice and you have to interact with the private guard gate and show ID. I was able to go in with my family, but we look like a typical suburban family, so that doesn't mean others wouldn't have more trouble. It's a pretty gross case of effectively privatizing a public resource.
That's the flip side of this: private land controlling the way into public land. It's a real problem in a lot of places, and an interesting thing to map someday.
American Prairie in Montana is an example going the other way: a nonprofit buying private land that surround public land and opening them to the public. It's somewhat contentious locally, but it shows how much the private parcels around public land shape who can actually use it.
That is going to depend on location. Most public land is way way out. There are often only a handful of visitors per month, and most of them won't get close to your land. Most of them are locals who know where the bounds are (and probably know you)
That matches my experience next to state game lands in PA. There's a few hunters in season who know where the lines, especially with OnX, Mostly quiet the rest of the year.
It means that nobody can build more houses "up the road" from you. That's the primary benefit. Unless the government sells the land, which this government has been trying to do in various places. This one issue is responsible for much of the reduction in republican support in Montana, for example
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Did you exclude NPS units intentionally?
It's blowing mind a bit that you made this and released it because I was on the verge of doing it myself. Very nice work.
Really curious about your data sources. Where are you getting all this stuff?
Thanks, that's really nice to hear. Happy to share:
- Listings: RentCast's API (licensed), pulled weekly.
- Parcel boundaries: state and county GIS services where they publish statewide parcels (about 20 states), and Realie (licensed) for the rest.
- Public land: USGS PAD-US 4.1, filtered to fee-owned, open-access land of 50+ acres.
- Elevation: USGS 3DEP point queries. Roads: Census TIGER. Flood: FEMA's National Flood Hazard Layer. Wildfire: Forest Service Wildfire Hazard Potential (2023). ZIP search: Census ZCTA centroids.
The free state parcel services were the biggest hunt: every state publishes differently, and a couple that looked open turned out to be test or internal-use-only endpoints.
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This is super cool. I love this use of public data to do something cool. The page seems like it's biggest value is to help potential property buyers find property they wouldn't easily be able to otherwise (that's what I like about it). Given that, seems like being able to filter on cost and size of lot would be useful filters on top.
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*in the US only.
Hi HN, I built this. Listings that say "borders state land" can't easily be checked: you open the county's GIS viewer and line up parcel lines against public-land maps by hand. I did that a lot while looking for land of my own, then automated it.
How it works, once a week:
1. About 700,000 active U.S. listings come in from a licensed listings API.
2. Each listing near public land gets its county parcel boundary, from state and county GIS services where they publish them and from a licensed parcel provider elsewhere. With no boundary, the page says so and measures from the listing point, but never claims a shared edge.
3. Public land is USGS PAD-US 4.1, narrowed to land an agency actually owns (Category = Fee, so no conservation easements), that's open to the public, and that's at least 50 acres.
4. Parcel and public land are compared in a local metric projection (shapely/geopandas): within (an inholding), bordering (the boundaries touch, and the shared edge is measured in feet), or adjacent (within 75 m, about a road's width).
Each property also gets the size of the connected public land behind it, its elevation (USGS 3DEP), road access (Census TIGER roads), FEMA flood zone and Forest Service wildfire hazard. The output is about 16,000 static pages with Leaflet maps on Cloudflare Pages, rebuilt every Monday on a Mac mini. ZIP search looks the ZIP up in your browser from Census centroids, so nothing you type is sent anywhere.
Things that were harder than expected:
- Lot sizes sometimes arrive in square feet in the acres field. A Birmingham, AL listing came through at 7,000 acres. Sizes are now checked against price, property type and the parcel itself, and corrected or withheld with a note.
- Condo and subdivision listings often resolve to the association's common tract, so a single town lot can appear to share miles of boundary. Those are flagged as shared parcels.
- PAD-US stores some units as one multipart polygon. My first "connected public land" figure for one Montana property was 69.7 million acres, about three-quarters of the state. Units are now split into pieces and joined only where they actually touch.
- Road centerlines and lot lines come from different agencies and are often tens of meters apart, so "does a road touch this parcel" needs a tolerance, and frontage only counts where the boundary runs along the road.
It's free, with no account and no cookies. There are free weekly email alerts for any search, starting Monday. I'd especially like to hear from anyone who has bought rural land: what should it measure that it doesn't?
> 1. About 700,000 active U.S. listings come in from a licensed listings API.
What API is that? It looks like you or the data broker are violating some NAR / MLS / State Compliance rules to me. You might want to look into those.
Not sure if you meant it that way, but this comes across as a bit hostile. Do you care to share some specific rules you think are being violated?
There are gazillion compliance laws, etc, but basic copyright laws commonly cover these things.
https://www.rentcast.io/terms-api
> You and We acknowledge and agree that, in the event of a third-party claim arising out of or relating to your access to or use of the RentCast API, or your possession, use, disclosure, display, resale, or distribution of the API Data, including any claim that such activities infringe any third-party’s intellectual property rights or do not comply with applicable laws and/or regulations, you, and not Us, will be responsible for the investigation, defense, settlement, and discharge of any such claim. You will promptly notify Us in writing of any such claim.
Database copyright isn't really a thing in the US.
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Which LLM did you use?
Mostly Claude Code. I have a background in 3D Design and Geospatial Mapping, the data sources and the decisions about what counts as "bordering" were mine
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I'd love to chat to you about this. I have been solo building in the real estate space for about 5 years now. I've finally got to a point where I make a roughly market salary from it, and I'm starting to venture wider into providing a listing service for everyone from FSBO's to large brokerages. Theres a huge opportunity to displace the position Zillow et al have, but it's riddled with legal challenges and risk (They've done a great job of making it hard to break in).
If you're up for a chat, please ping me! This is pretty cool and I'm wondering if theres a collaboration, or if I can straight up use some of what you've made.
Hey, I mean this in as kind a way as possible, but I actually don’t think the government should pay for the fence line!
If you wouldn’t even pay for it yourself, as pretty much the sole beneficiary and someone who could afford it but would rather the money go elsewhere, why would it make sense for other taxpayers to pay for it?
Isn’t the premise of “you may as well own that land” the entire appeal of living next to public land anyway?
My family used to live next to state land. The state can be very pissy about its land. If the fence line is on the state land, which it almost certainly is barring a surveying error when it was put up, it is entirely possible that if he fixed it, he would actually get in trouble with the state. My default presumption, without checking, is not only that it would not be allowed, but that this is also very much not a "better to ask forgiveness than permission" situation either.
> Hey, I mean this in as kind a way as possible, but I actually don’t think the government should pay for the fence line!
Which is a fine option, but it should be something agreed to by both parties. You can't just hand over a cost like that, and if you buy property with some kind of agreement this choice is baked into the original price. It makes perfect sense for the government to uphold agreements it has made.
Secondly - if they did own the fence line, it'd be on the government to come and fix it when one of their trees breaks it, surely?
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Put up your own fence inside of your property line that you can keep up to your needs and standards.
That's a good point. What about wetlands? My property has a terrible mosquito problem and I just found out there is a pond/swamp hidden in the brush. Since it's my property, I'll take steps to reduce the mosquito problem next year but if it was public land, that'd probably wouldn't be acceptable.
If you throw some mosquito dunks with BT into any given water body small enough it doesn't have a name, nobody is going to come after you. I think it's probably a pretty prosocial thing to do, unless I'm missing something
My internal dialog can imagine my biologist wife yelling at you already.
Honestly i do not know the full scope of this one, but if there's one thing I've learnt from observing her work over the last decade...it's humans need to stop adding chemicals to water bodies with the goal of thinking they're helping something.
I will ask her and report back...
I can imagine her having some long explanation about the unknown risks of man spreading this substance, even if its not a chemical agent. I lean on the edge of listening to Grandpa Simpson on these kind of things: https://i.imgur.com/MdjduDH.png
The mosquitoes don't exist in isolation though. Isn't this exactly how food chains / ecosystems work? You can't remove a tier without consequences.
The path to hell is paved with good intentions: https://en.wikipedia.org/wiki/Cane_toads_in_Australia
It might well be safe, but the question is what are the downstream affects of reducing the population of mosquitos (or other bugs in the water that this substance impacts). Maybe they've exclusively positive, but I assure you determining that is no walk in the park.
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