We had literally that until 9/11

In the 90s, it was the norm for people in northern maine to cross into canada and vice versa, like weekly, to do certain shopping. We regularly took advantage of the low value of the Canadian dollar back then, and every grocery store in the US had daily Canadian customers.

Crossing the border was pretty much just agreeing that you weren't trafficking any specific produce. That's it.

Fort Kent, Maine is literally across a river from Canada. The bridge and border crossing is basically part of the town, and it was a normal daily thing to drive to the other side of the river and do something in Canada, like eat at the nice Chinese restaurant, "The Maple Leaf".

Every northern maine school had regular field trips across the border.

The two communities were basically one. There was no border. It was just a line on a map and a nod to your local friend who worked in the booth.

The southern border used to be similarly uncontrolled. The "Immigrants" and migrant workers who pick your produce have been a normal thing in US history forever. They wouldn't stay in the US, because the border was so lax they didn't expect any trouble coming back in the next time they need the paycheck.

The reaction to 9/11 was atrocious. All it did was kill already struggling communities in rural areas, hurt hardworking Americans, waste billions of taxpayer dollars on "Super duper important" airport scanners sold by a friend of the Bush admin, which then sat unused in a warehouse and we stopped using them entirely shortly after.