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.

I owned a house on 60 acres in Washington State that was bordered on 2 sides by state land (WA DNR). It was generally great and the only time I closed my gate was actually these two weeks of every year for regular rifle deer season. I never had issues with hunters coming on my property (I did give some friends permission to bow hunt). My driveway was about a mile long and had to cross DNR land to reach my property, but I had an easement. The easements typically have a 35 year expiration and it would take extreme circumstances for the state not to renew an existing easement. Complete and total privacy is really nice, but it's certainly a lot of effort and money to maintain a remote property of that size with a large house. I had to travel to SF a lot for work and that was certainly not ideal: 2.5 hour drive minimum to a tiny airport that only served Seattle, then on to SF.

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.

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?

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?

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.

*in the US only.

Are you using this for parcel data? Or are you sourcing them directly from every county

https://www.kaggle.com/datasets/landrecordsus/us-parcel-laye...

Did you exclude NPS units intentionally?

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?

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.

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.

> 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.

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)

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

> 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.

Which LLM did you use?