It shouldn't be a surprise that the Southern states are the biggest polluters in the US. This region's use of coal and oil in energy production and their choice of vehicles means that they account for 40% of the pollution produced in the US. Per capita pollution produced in California is just half what is produced in Texas. It may be a simplistic example of this reality but waiting to be picked up at airports in California and Texas shows this clearly. In California, you see few trucks and many Priuses and Teslas. In Texas, you see many more trucks and large SUVs.