Since when do trading hubs and dens of depravity produce their own food?

Also, Fallout's (in)ability to generate roving NPCs in substantial numbers notwithstanding, 6000 people is not a "huge, bustling city". Without modern farming techniques and technology, at least 2400 of those people would be farmers. London, in the 13th century, had 45000 people in it, just for comparison.

@jdunlop: The people living in cities were generally not farmers. Some of them may have owned farms, but they most likely did not work those farms themselves. Cities, almost by definition, exist for the purpose of trade and industry. Farming is much better done in the country side.

@AlexP - For sure. But the OP didn't say that there was a large supporting population surrounding the city. In pre-industrial times, the supporting population was much larger than the urban population, by necessity.

@Patricia: Lake Mead and the Colorado ofc

Lake Mead and Colorado river are a fair distance away from Las Vegas. Someone has to maintain an aqueduct.

6,000 people, even if inhabiting only the Strip area would make it not "bustling" but rather "desolate".

@Alexander: Then what is bustling

@DT Cooper 100,000 is just the number of people who normally work there.

@Alexander got my point. There is an elaborate infrastructure for supplying water to Las Vegas. It gets about 4 inches a year of rainfall, mainly in the winter. For it to be habitable either someone is maintaining the Hoover Dam complex and an aqueduct, and controlling the water intakes in Lake Mead, or they have built a system for capturing, storing, and distributing their limited rainfall. Either way, it is going to take organization. Any farming in the region would have to be irrigated, requiring yet more water management and distribution.

@Patricia Shanahan: I wonder if there are any rivers nearby that the people there could just collect water from. Hm?

@Alexander: 6,000 people is a city in my world. It’s a post-apocalypse

@DT Cooper But are they going to inhabit existing buildings? If yes, it might be hard to find those 6,000 in vast ruins.

@Alexander: No they only inhabit a few buildings

@Alexander: You need rather more than an aqueduct, since the max elevation of Lake Mead is about 600 ft/200 m below the elevation of Las Vegas. You need pumps, and people to maintain them.

You have more problems than just the food supply. I assume your post-apocalypse world is fairly low-tech, no? In which case, how do you get customers for your gambling dens and so on? There really IS nothing in the area that isn't supported by technology: you have to cross several hundred miles/km of desert to get there. And most of the year, you can't really survive in any degree of comfort without air conditioning. (Seriously, I have seen it be 113 F/45 C at 3 AM.)

@jamesqf: They make use of air conditioners made to use batteries.

@DT Cooper: Battery powered air conditioners are even more of a problem. Where do they get suitable high-tech batteries? Far easier to maintain the turbines at Hoover Dam, and a power line from there to Las Vegas. (Indeed, if you want a post-apocalyptic gambling mecca, Reno would work a lot better.)

Las Vegas has an extra problem in that it never had a lot of water in general, even compared to some other areas in the American desert southwest. Las Vegas generally got so big due to logistical needs, primarily the railroad, the Hoover Dam, and gambling. A lot of food gets shipped in from California. People have been trying hydroponics in recent years but it hasn't produced notable results yet. It's unlikely it will ever be a self-sufficient city without massive changes in technology.

@user2352714: Well, yeah, I need to make it work

@DTCooper What I'm saying is you may not be able to. Las Vegas as a city was built because it was strategically placed, not because it was a viable settlement on its own. Nevada right now only imports 2% of the food it needs for its population to survive. Vegas might not work as a metropolis in a post-apocalyptic scenario unless it is part of a larger power supporting it with imports as it is now. m.lasvegassun.com/news/2015/dec/07/…