The majority of the billionaires in the US live in the Dallas Fort Worth area - DFW - and those billionaires have quite a bit more than 1 billion, up to 20+ billion owned by Sam Walton's daughter who lives there. Next to her is Stemmons with about 9-10 billion, then others less than that but above 1 billion. Those are the known billionaires in that area.
All billionaires in the Houston area are stuck in the 1 billion, don't make it to 2 billion.
blame the refinery smog