Explain why so many oil refineries were set up along the southeastern border of Texas.

A lot of drilling techniques and practices, led to the untapping of natural resources and oil refineries.

Explanation:

Around the year 2000s, in early part of those years, there was sudden boom of oil refineries in Texas. This boom was because there were a lot of drilling technologies and practices to untap the natural resources in that part of the country leading to a lot of oil refineries.

This came out to be big potential for a lot of money, growth and development for the economy.

the answer is a, salt plain