The United States of America (USA)
is one of the world’s most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. The geography and climate of the United States is also extremely diverse, and it is home to a wide variety of wildlife. The United States has the world’s largest national economy, with an estimated GDP in 2013 of $16.7 trillion. The U.S. has the highest mean and second-highest median household income in the OECD as well as the highest average wage.