History: Black And White Photos Of New York City, United States

The phrase "the United States" was originally treated as plural—e.g., "the United States are"—including in the Thirteenth Amendment to the United States Constitution, ratified in 1865. It became common to treat it as singular—e.g., "the United States is"—after the end of the Civil War. The singular form is now standard; the plural form is retained in the idiom "these United States".
Geography, climate, and environment
The land area of the contiguous United States is approximately 1.9 billion acres (770 million hectares). Alaska, separated from the contiguous United States by Canada, is the largest state at 365 million acres (150 million hectares). Hawaii, occupying an archipelago in the central Pacific, southwest of North America, has just over 4 million acres (1.6 million hectares). The United States is the world's third or fourth largest nation by total area (land and water), ranking behind Russia and Canada and just above or below China. The ranking varies depending on how two territories disputed by China and India are counted and how the total size of the United States is calculated: the CIA World Factbook gives 3,794,101 square miles (9,826,675 km2), the United Nations Statistics Division gives 3,717,813 sq mi (9,629,091 km2), and the Encyclopædia Britannica gives 3,676,486 sq mi (9,522,055 km2). Including only land area, the United States is third in size behind Russia and China, just ahead of Canada.