This in an interesting question, and it has a surprising answer. You might expect that the largest U.S. city would be one of the most populous cities, such as New York, Los Angeles, or Chicago. However, this is not the case.
According to the U.S. Census Bureau, the largest U.S. city in land area is Sitka, Alaska. Although it has a population of just 8,986, Sitka encompasses a whopping 2,847 square miles an area roughly equal to the states of Rhode Island and Delaware put together.
Following Sitka on the list are two other cities in Alaska. Juneau (population 30,987), which covers 2,717 square miles, ranks as the country's second-largest city. Anchorage (population 275,043), which encompasses 1,697 square miles, ranks as the third-largest.
So what are these three Alaskan cities doing at the top of the list? The answer is that they are not just cities; they are city-boroughs. A borough is an administrative unit that is much like a county. All of the other U.S. states except Louisiana are divided into counties, but Alaska is divided into 16 boroughs and a large, thinly populated area that is referred to as the unorganized borough. (Louisiana's administrative divisions are called parishes.)
In a city-borough, the city and the borough comprise a single government, and they have the same boundaries, although the actual urban area might represent just a small part of the borough. For example, most of the city-borough of Sitka is a scenic wilderness of mountains, forests, glaciers, and icefields; the urbanized area represents only a small part of the total area.
Below is a complete list of the 25 largest U.S. cities by land area. Many of the cities in the list that are located in the "Lower 48" states are similar to Alaska's city-boroughs: they are cities that have become dramatically larger by consolidating with the counties in which they are located. For example, Anaconda, Montana (#5 in the list), consolidated with Deer Lodge County in 1977; the city and the county now share the same boundaries.
The 25 Largest U.S. Cities by Land Area
(Question submitted by a 9th-grade teacher at the Christ School in Orlando, Florida.)