Chennai metropolitan area

Greater Chennai Metropolitan Area, or simply the Chennai Metropolitan Area (CMA), is fourth-most populous metropolitan area in India and the 35th most populous in the world. The CMA consists of the core city of Chennai, which is coterminous with the Chennai district, and its suburbs in Kanchipuram, Chengalpattu, Thiruvallur and Ranipet districts. The Chennai Metropolitan Development Authority (CMDA) is the nodal agency that handles town planning and development within the metro area. In 1974, an area encompassing 1189 km2 around the city was designated as the metropolitan area which was subsequently expanded to 5904 km2 in 2022.

History
In 1974, the Madras metropolitan area comprised a total extent of 1189 km2. In 2011, first plans to expand the metropolitan area were proposed by Chennai Metropolitan Development Authority (CMDA) as several settlements on the outer vicinity had been undergoing rapid development and had to be incorporated under the CMDA planning strategy. While other metropolises in India had already redefined their respective metropolitan regions to include much larger areas, CMA had not been altered since it was first defined in 1974. In July 2012, the CMDA suggested two options to the Government of Tamil Nadu for expanding the area with the first option including the whole of the Chennai, seven taluks each from Tiruvallur and Kancheepuram districts extending up to 4459 km2 and the second option including the whole of Chennai, Tiruvallur and Kancheepuram districts and Arakkonam taluk extending to a total of 8878 km2. In July 2017, the Government of Tamil Nadu announced its intention to expand the CMA to 8878 km2 with the whole process expected to be completed by July 2018.

On 22 January 2018, Government of Tamil Nadu issued a Government order to declare the intention to include additional areas in the Chennai Metropolitan Planning Area under the Tamil Nadu Town and Country Planning Act, 1971. As per the act, the government is required to allow reasonable opportunity (two months) for inhabitants, local authorities and institutions in the area to comment upon or object to such an expansion proposals and few objections were received including a public interest litigation filed at the Madras High Court in March 2018. The plan was later modified and in October 2022, the metropolitan area was expanded to 5904 km2.

Distribution and composition
The metropolitan area consists of four municipal corporations (Greater Chennai, Tambaram, Avadi, Kancheepuram), 12 municipalities (Arakkonam, Mangadu, Kundrathur, Poonamallee, Thiruverkadu, Thiruninravur, Tiruvallur, Tiruttani, Maraimalai Nagar, Chengalpattu, Ponneri, Guduvancheri) and other smaller panchayats spread across the districts of Chennai, Thiruvallur, Kancheepuram, Chengalpattu and Ranipet. The planning and development is overseen by the Chennai Metropolitan Development Authority (CMDA), a Tamil Nadu State Government organisation in charge of town in the region. CMA region has about 3,000 water bodies. CMDA has proposed to trifurcate the CMA into three zones – Central, North and South.

Administration
The CMDA regulates developments in the Chennai metropolitan area through the issuance of planning permission under section 49 of the Tamil Nadu Town and Country Planning Act 1971.

Economy
, the GDP of the metropolitan is estimated at 143.9 billion, ranking it amongst the most productive metro areas of India. Chennai has a broad industrial base in the automobile, computer, technology, hardware manufacturing and healthcare sectors. , the city is India's second-largest exporter of information technology (IT) and business process outsourcing (BPO) services. A major part of India's automobile industry is located in and around the city thus earning it the nickname "Detroit of India". Known as the "Gateway of South India", Chennai is the third-most visited city in India by international tourists according to Euromonitor.