Why are property limits so fuzzy in North American suburbs?

> Sidewalks typically merge with the front lawn; there is no visible property limit.

Cities typically have easements for things like sidewalks and underground utilities. You have the right to use that space for normal purposes, with the understanding that the city may dig it up to make improvements or repairs. You may also find one day that they have allowed a utility company to install an equipment box in the easement area. When shopping for a house, look for the existing equipment boxes nearby, as the city will usually try to add new ones there. But no guarantees.

Easements are also used between neighbors. It sometimes happens that a piece of property is "land-locked" with no access to a road. An easement will allow that property owner to construct and/or use a driveway across their neighbor's land. Often the land-locked owner has to compensate the other owner for creation of the easement, as it diminishes the value of their land.

https://en.wikipedia.org/wiki/Easement#Access_easement

The property boundaries are not always visible, but they are defined in government records (in the US, typically with the local property tax assessor’s office). It’s not uncommon for a lot boundary to be temporarily marked with stakes and twine during a construction project such as building a house on an empty lot.

Ultimately, if an object like a tree is on your property, even if it’s right up to the line, that tree is yours (but your neighbor also has the right to prune any branches that extend onto their property). Your neighbor could take down the laundry pole if they wanted to.

There's some variation even within North America. In my experience denser areas are more likely to have fences than rural areas. It even seems that in California people are more likely to have fences than on the east coast (given similar density).

You're asking the question in the opposite way.

What is it that makes people in South America surround their houses with huge walls and fences?

A lot of the mystique of suburbia is the illusion of being the owner of a house in the country. It’s more of a tradition now, as modern developments have minimal yards.

You’re also selling the idea that there isn’t any crime. Instead of keeping the world off your property, you’ve moved to another world.

In some developments, they deliberately site the houses so that if you look directly out the front windows, you see the space between the two houses across the street.

We have a fence around our property. That fence is not on the property line.

The previous owner needed a level place for a swingset for his kids, so the next-door neighbor let him use a bit of the neighbor's land. They built the fence so the swingset was on my side of the fence, even though it's the neighbor's land. The fence doesn't change anything. (Though I suppose if I wanted to be nasty, I could claim squatter's rights or some such legal concept, and maybe take that bit. But I don't want to. Ripping off people that were nice to someone isn't how I want to live.)

Some people like to have a fenced space, especially in their back yard (no neighborhood dogs running up to the small kids). Some don't (extended sight lines, more of a feeling of neighborliness). But the fences don't matter. The property lines are still where they are, even if you can't see them.

A few people in my neighborhood have fences/walls. Most are those incredibly ugly white plastic things. I know where my corner markers are. I try not to put stuff beyond my boundary, but it generally doesn't really make a difference as three sides of my property is wooded/wild, and I'm probably the only person to go in there. The town "owns" 10' on either side of the road in front, so I try not to put much there except for my mailbox and a couple of small flower patches. Note: Kids do not recognize boundaries. They will ride their bikes on my driveway, across my yard, wherever they feel like it. Smart people, those kids.

A family member had a career in title insurance and it does matter if the neighbor puts a fence on your property. You'll have trouble getting a loan for the property, or even selling it, because while the county has the maps, and the surveyor will mark the lines, the neighbor is claiming that property with his fence. There are agricultural exceptions to this from what I remember... Also If a neighbor fences part of your property, then breaks a leg on your property behind their fence, your homeowners insurance will be responsible for the bill up to the limits in your policy.

You as a property owner can pay to get your lot lines surveyed, but building cinder block or concrete walls between lots is generally not done due to cost, aesthetics since its considered an eyesore, doesn't add tangible value for the current owners and can hamper shared use items like the laundry pole you mentioned.

I wouldn't want to live on a property blighted by a cinder block wall. With the risk of earthquakes here on the West Coast you would want a good foundation and rebar/concrete reinforcement for such a wall as well.

Funny you say that because I had to point out to a new new neighbor last summer that he was driving on my property. My fence at that point was probably about 50' inside the actual property line (rural area), but he was used to living in the suburbs where everyone put their fence exactly on the property line, so he really had no idea. The issue was even more confused by the fact that there's a gap between our respective properties that's owned by the county.

In my area (suburban Twin Cities, MN, USA), while you may not see visible property markers, they are nearly always there in the form of buried metal property marking pins. These are typically just an inch or two below the surface.

We recently built a fence, and prior to that went around the four corners of the yard with a toy metal detector and were able to locate all four pins, marking them with flags for the fence installation crew.