I cant help but start out by acknowledging sharing this chart with @Eric P. showing that the Midwest has the highest home-ownership in the Nation by a long shot with New York and California having the lowest.
With that out of the way I will share some more charts I think will help @Peter Aziz question as to why the rental rate is so high when renting is cheaper than a mortgage in many areas of the City.
Prior to the 1970s the majority of middle class and working class people lived in the City of St. Louis while the upper/business class lived in suburbs just west of the City.
During the 1970s a large majority of the middle class moved to suburbs to the West and South of the City into classic suburban neighborhoods. According to Census home ownership rates in Arnold (40 minutes South) and St. Peters (40 minutes West) are all above 80%. This expansion outward has continued with most new homes being built directly west of the City.
The City of St. Louis is not part of St. Louis County and the loss of property tax revenue hurt the City in terms of the school system and other infrastructure. Communities on the South Side benefited from strong catholic diocese schools and the fact that their businesses were in between the suburbs and downtown business district and sports arenas. Many of the diocese schools have closed making it harder to raise kids in the South Side. However, many of the regions most famous restaurants and attractions remain in that area and convenient highway access makes it a good place for to live for a young professional. In these areas the tenants could probably afford to buy but chose to rent until they can buy in another area. The Cortex, Soulard, CWE and the Grove are all similar and are areas that have the potential for crazy returns.
The North Side of St. Louis was basically left in the dust and crime and unemployment ran rampant. There is not much opportunity in this area.
The tricky part about St. Louis is the neighborhood can change in a block and without knowing the City or walking the streets yourself it is very hard to tell which area you are in. There are also literally 90 municipalities in St. Louis County with different rules and costs. I am currently staying out of the City all together and focusing on less profitable but more consistent investments in the suburbs