If you mean only involving the US, than the Civil War.
yes it was
Largest military AND civilian casualty and death rate.
The US civil war
While certainly an important event in US history, the US Civil War didn't "lead" or "start" the study of US History.
The Us Civil War was the bloodiest war recorded in US history.
The statement that US history is not taught past the Vietnam War is not correct. US colleges and secondary schools have quite different US history boundaries. There is a mass of US history running past the War in Vietnam.
It was the largest and most devastating war in human history.
that is very easy it is the Civil War :) and second would be World War II
Abraham Lincoln?
The largest tsunami in the world and the US Happened in Liyuta bay, Alaska on July 9th, 1958.
Traditionally it has been the US Civil War and WW2.
The American Civil War