The richest county in the entire United States is right here in Texas. In fact, it’s only about an hours drive northwest of Corpus Christi. Income taxes filed in McMullen County show the highest adjusted gross incomes in the nation, according to a report from Bloomberg News. 
The data is based on last year’s tax returns and comes from Syracuse University’s Transactional Records Access Clearinghouse. According to the study, the average adjusted gross income of rural McMullen County was $303,717 in 2015, the latest year available.
Coming in second was Teton County in Wyoming, another rural area, with $248,949. Third went to the urban giant of New York County, which includes New York City, at $210,233.
Number four is also in Texas: Glasscock County near Midland at $181,375.
The reason for the largess of both Texas counties comes, of course, from oil and gas. McMullen, with a population of about 1,000 people, is in the heart of the Eagle Ford Shale Play, while Glasscock, population 1,200, is in West Texas in the Barnett shale patch. 
"I joke that oil and gas finally made ranching profitable," Thomas Tunstall, research director for the Institute for Economic Development at the University of Texas at San Antonio, told Bloomberg.