@Sam Pant - Before jumping into specific neighborhoods, take a look at more macro-sites like city-data.com to get a grasp on population growth/decline, median home values, crime trends, job growth....etc.  

I really like that the income and house values have shown strong growth and that the crime rate has been declining, but what concerns me is the declining population.

The background for this property is It’s a condominium near a very high population area.

The population of the town is about 10k w low unemployment but the 10k will affect how you get those empty lots filled in.

Unless you are buying super cheap homes for under 100k each, or are purchasing homes in areas with consistently declining population, you will likely not hit these 'rules'.The median home in the US is valued at 231k according to zillow. 

The population of the city has grown consistently for the last 10 years, it's relatively close to where I live, and I am think it has the potential to be a great rental market.

Look at the population increase estimates on Charlotte, PHX, Huntsville, ect...

I would recommend Columbus because of our job and population growth.

@Alexander ParadaHouston as a market is a good one, Texas in general has one of the lowest unemployment rates and highest population growths in the country.

There is a long list of categories that you can look up from the population count and age statistics, Housing stats including median home values, rental and vacancy rates, crime rates and lots more.