How to find existing multi family properties in an area?

[Matthew Patrick]

Hey all, 

I was doing some research and reading this article: https://www.biggerpockets.com/blog/2015/11/16/how-...  

A partner investor and I was doing our diligence on a potential property, but had the idea of converting it into a multi-family. My background work would first be to see if the area is pro-multi family. So I wanted to know, Is there a tool or procedure you use to find all the existing multi-family properties in a given area? 

To refine the question, I am not looking for Multi-families for sale, ie. Loopnet.com or by filtering my search on Realtor.com

thanks in advance for your help!