Atlanta is the capital and most populous city of Georgia, in the United States. It is the county seat of Fulton County, although a portion of the city (the 1909 annex) is located in DeKalb County. According to the latest census estimates (as of July 2005), the city has a population of approximately 419,122 and the Atlanta metropolitan area totaled 4,917,717. Atlanta has long been considered the economic powerhouse of the Southern United States and is arguably a poster-child for cities worldwide experiencing rapid urban sprawl, population growth, and commercial development. As a result, Atlanta is a common case study for college students who study urban geography around the globe.Atlanta is circled by Interstate 285, called the "Perimeter" by locals, which has come to delineate the interior of the city from the surrounding suburbs. This has given rise to the terms ITP (Inside The Perimeter) and OTP (Outside The Perimeter) to describe area neighborhoods, residents, and businesses. In this respect, the Perimeter plays a social and geographical role similar to that of the Capital Beltway around Washington, DC.Atlanta has such a great economic impact on the state and the surrounding region that cities and towns up to 45 miles away are considered exurbs, defined by the fact that people depend on their livelihoods by commuting to work in the city, rapidly growing what is called Metro Atlanta. Atlanta is one of the most prosperous cities in the United States and is often referred to as the unofficial "capital of the South". Today Atlanta is one of the most economically important Southeastern cities along with Birmingham, Charlotte, Memphis, Miami, and New Orleans.The city is also an especially important cultural and economic center for African-Americans; Atlanta has not had a non-black mayor since 1974, and in recent decades nearly all Fire Chiefs, Police Chiefs, and other government officials have been African American. Atlanta is also very important in making famous Hip-Hop/Rappers who call Atlanta A-Town.Common colloquialisms for the city include A Town, The A-T-L (based on its airport code), and The A, which is short for The ATL.