The City and Borough of Sitka, formerly New Archangel under Russian rule, is a unified city-borough located on Baranof Island and the southern half of Chichagof Island in the Alexander Archipelago of the Pacific Ocean (part of the Alaska Panhandle), in the U.S. state of Alaska. It is the largest city-borough in the US, with a land area of 2,870.3 mi2 (7,434.1 km2) and a total area (including water area) of 4,811.4 mi2 (12,460.8 km2). With a population of 8,881 in 2010, Sitka is the fourth-largest city by population in Alaska. Urban Sitka (), the part that is usually thought of as the "city" of Sitka, is situated on the west side of Baranof Island.
According to the United States Census Bureau, the borough is the second largest incorporated city by area in the U.S., with a total area of 4,811.5 square miles (12,461.7 km2), with 2,874.0 square miles (7,444 km2) being land and 1,937.6 square miles (5,018 km2) of it, or 40.27%, being water. Yakutat is the largest incorporated area in the U.S.
Sitka displaced Juneau, Alaska as the largest incorporated city in the United States upon the 2000 incorporation with 2,874 square miles (7,440 km2) of incorporated area. Juneau's incorporated area is 2,717 square miles (7,040 km2). Jacksonville, Florida, is the largest city in area in the contiguous 48 states at 758 square miles (1,960 km2).