Ajo will always have border patrol jobs.  

There's plenty of Markets from Western PA all the way to the western border of Indiana that offer great entry points, affordable rehab costs, antiquated houses, emerging neighborhoods. 

My team has been investing in the Memphis market since 2010.Just recently closed on a 144 unit place in Desoto county just across border and was 96% occupied.

Newbie investor looking for multifamily properties in RI close to MA border. 

Consider Grosse Pointe Park (it borders Detroit) or Grosse pointe Woods. 

I'd like to buy, if possible, close to two of those borders so the development front hits it from both sides.

You can check with TD and Royal Bank in Canada to see if they will refi your US properties, as they have cross border branches.

North Tulsa (north of the brady arts district, within the Booker T school distric) and South OKC (bordering the river) are historically rougher, South Tulsa and North OKC are historically more affluent.

These are just the ones inside of 610 which makes up the border of this image)

Although I live in Ontario Canada, I would think that this question is relevant on both sides of the border.