Scuttle

The only settlement that can be used as a jumping-off point for expeditions into the Great Salt Lake region, even if its whole population has an air of... concern at best, fear at worst.
Fear that the town and everyone in it may just vanish for some reason, like every other settle seems to in the area. Eventually.
They don't bother with defense, despite the fear. They know that if Scuttle goes, everything else in the Salt Lake that hasn't vanished will starve instead. Then the bones will probably fade from existence as well. It's good leverage.
They don't bother with law, either. Or rather, no law bothers with Scuttle. Everyone's so jumpy that it's basically committing death by shaky gunman or a squad of superstitious Aces all marked up with Salt-Chalk.

I've never seen a town so dirty as Scuttle.
Even the undercity back home had an air of order, a feeling of safety you could get if you were sitting in your hab block with the doors locked, and knowledge that your neighbors were in it together with you. A sense of community, I guess.
There? It's like 500,000 rats tearing at each other over food, water, space, and just because. If one rat isn't going to gouge that other for stepping into it's square inch of territory, who is? After all, the invader could have been coming for that parcel of land.
There wasn't a moment I didn't have one hand on my pistol, and everyone I passed was the same. The only one I didn't see hovering around a weapon was the M leading me through the crouds. 
All painted in symbols, I can only assume he had something that could be counted as a weapon. 
At least he thought he did.

Government

The settlement lacks any sort of overarching government on paper. There isn't a town hall, or even a tradition of selecting new leaders.
Scuttle is lead by whoever can get people to listen to them at the time, a notoriously hard task for both outsiders and those born and raised in town.
In practice, there is a semi-flexible series of regular leaders that rise out of the local scavenger leagues, cults, gangs, and the occasional Ace with a conscience to try and better living in Scuttle or an agenda.

Defences

While the settlement is walled, it must be to stop Tech-Horrors from simply sliding in during the night, the different groups of interest maintain it as best they can without spending more resources than anyone else.
They have no militia, something that would be common and expected anywhere else, relying entirely upon the inhabitants of the town and their trigger fingers for defense. Te closest thing to law enforcement would be the bike gangs that have, a handful of times in the past, rode out in a tenuous alliance to deal with threats outside the walls.

No one in Scuttle is under the illusions that an event like that is common or likely to happen, even if a force that would crush each and every inhabitant was on it's way. It would take a very unlikely combination of leaders and situation.

Infrastructure

Almost all infrastructure, what little the town has, is centered around picking the bones of the cities found within the borders of the Great Salt Lake. Vehicle pools, heavy tools pulled from drydocks, scrapyards and some surprisingly efficient processing yards to melt down old world metals and scrap electronic devices.
Most of these sites are built on what little old-world foundations. Patches of paved roads and capstones of buildings, still standing against father time, that must have once held a neighborhood before being subsumed by the salt.

Type

Outpost / Base