The Greater Phx area also has more places to expand, but be cautious of "island" developments that are separated from bigger cities. 

Out of these areas, Franklinton and Linden are seeing some of the most developments.

The biggest hurdle I see with arbitrage is developing a pitch to use when approaching landlords, which you can probably do with a little research on BP and ChatGPT.

I am considering working with a property developer in NJ to buy land, build a duplex/triplex and sell it (6-9 month time horizon).  

Literally your title is "business development" and you are saying that you "not here to sell you ANYTHING?"  

Not to mention the economic development steps the town is taking in ensuring the growth of town (roads, schools, zoning) stays on par with the future expected population growth and new jobs that are going to be a result of the new factories opening.  

you have to learn land entitlement. we identified a site today for hotel development that was an 18000 sq ft lot.

As there is a general flight to affordability, the new developments don't fill as quickly, and rely on concessions and/or lower asking rents to fill up.  

In Columbus, you can still find the 1% rule and there's amazing appreciation potential due to how much population growth, job growth, and companies moving/developing there (recently Anduril just announced another 4,000 jobs coming to Columbus Ohio on top of Intel, Google, Amazon, FB, Nationwide, Ohio State University, etc.).

very high risk even I only do them with very specific investors in mind and a plan. we dont flip land we develop every one.