Pittsburgh, located at the confluence of the Ohio, Allegheny, and Monongahela rivers, played a crucial role in American history. Founded in 1758, it became a strategic military site during the French and Indian War. The city's growth accelerated in the 19th century with the rise of the steel industry, making it a hub for manufacturing and immigration. By the mid-20th century, Pittsburgh was known as the "Steel City," producing a significant portion of the nation's steel. However, the decline of the steel industry in the 1970s led to economic challenges. Today, Pittsburgh has transformed into a center for healthcare, education, and technology.