US in 1945.
The chariot was first used as a weapon by the Indo-Iranians from 1700 to 500 BCE. The chariot was built in eastern Europe.
The first beam bridge was built in America
America
Camden
The first Subway in North America opened in Boston in 1897.
The first known theater in North America was built in Williamsburg, Virginia.
Contrary to what some people believe the Ford Model T was not the first car made in America and was not even the first car Henry Ford built. Henry Ford's first car was the Quadricycle built in 1896 over 11 years before the Model T. The first car built in America was the Duryea built in 1893.
The first ship was built by Columbus. He was in search of Indian subcontienent and accidently reached America.
Cumberland Road
1830.
The united states researched, built, tested and created the first atomic weapon.