The most populous cities in area code 321 are: Cocoa, Orlando, Melbourne, Winter Park, and Titusville.

Other cities in the 321 area code include: Cocoa Beach, Kissimmee, Sanford, Saint Cloud, Christmas, Oviedo, Satellite Beach, Geneva, Apopka, Montverde, Kenansville, and Cape Canaveral.

Cocoa is a city in Brevard County, Florida. The population was 17,140 at the 2010 United States Census. It is part of the Palm Bay – Melbourne – Titusville Metropolitan Statistical Area.

Orlando is a city in the U.S. state of Florida and the county seat of Orange County. Located in Central Florida, it is the center of the Orlando metropolitan area, which had a population of 2,387,138, according to U.S. Census Bureau figures released in March 2016, making it the 24th-largest metropolitan area in the United States, the sixth-largest metropolitan area in the Southern United States, and the third-largest metropolitan area in Florida. As of 2015, Orlando had an estimated city-proper population of 270,934, making it the 73rd-largest city in the United States, the fourth-largest city in Florida, and the state's largest inland city.The City of Orlando is nicknamed "The City Beautiful," and its symbol is the fountain at Lake Eola. Orlando is also known as "The Theme Park Capital of the World" and in 2014 its tourist attractions and events drew more than 62 million visitors. The Orlando International Airport (MCO) is the thirteenth-busiest airport in the United States and the 29th-busiest in the world. Buddy Dyer is Orlando's mayor.As one of the world's most visited tourist destinations, Orlando's famous attractions form the backbone of its tourism industry: Walt Disney World, located approximately 21 miles (34 km) southwest of Downtown Orlando in Bay Lake, opened by the Walt Disney Company in 1971; the Universal Orlando Resort, opened in 1999 as a major expansion of Universal Studios Florida. With the exception of Walt Disney World, most major attractions are located along International Drive. The city is also one of the busiest American cities for conferences and conventions; the Orange County Convention Center is the second-largest convention facility in the United States.Like other major cities in the Sun Belt, Orlando grew rapidly during the 1980s and into the first decade of the 21st century, mostly due to the success of Walt Disney World, which was opened on October 1, 1971. Orlando is home to the University of Central Florida, which is the largest university campus in the United States in terms of enrollment as of 2015 . In 2010, Orlando was listed as a "Gamma−" level of world-city in the World Cities Study Group's inventory. Orlando ranks as the fourth-most popular American city based on where people want to live according to a 2009 Pew Research Center study.

Melbourne / ˈ m ɛ l b ər n / is a city in Brevard County, Florida, United States. As of the 2010 census, the population was 76,068. The municipality is the second-largest in the county by both size and population. Melbourne is a principal city of the Palm Bay – Melbourne – Titusville, Florida Metropolitan Statistical Area. In 1969 the city was expanded by merging with nearby Eau Gallie.

The 321 area code lies within the Eastern Daylight Time Zone (or EDT). The current time in Eastern Daylight Time is 10:33 AM on Sep 28, 2023.

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