Fahrenheit was invented first in 1724. The United States started using Fahrenheit. Celsius was proposed in 1742. Celsius was selected by the Metre Convention in 1875 as the international standard (mostly because France was already using it). Everyone else except the United States and Liberia has slowly switched to the international/scientific standard (now known as SI) because having multiple standards is an ongoing cost but switching standards is a one-time cost.
The United States is sentimentally attached to its pre-SI units more than they care about international inter-operability – so they continue to endure the ongoing cost of juggling a separate system of units while also using SI units in most science and some engineering work.
The United States is sentimentally attached to its pre-SI units more than they care about international inter-operability – so they continue to endure the ongoing cost of juggling a separate system of units while also using SI units in most science and some engineering work.