The National Capital Region (NCR), sometimes referred to as Delhi-NCR, has an important place in the history of the South Asian subcontinent and continues to play an essential role as the home for the capital city of India. DelhiNCR is an ever-expanding interstate planning region with the National Capital Territory (NCT) at its heart (Figure 1). The NCT of Delhi is a union territory of India with an estimated population of about 22.5 million in 2021. The region has seen a phenomenal population boom in the last few decades and its population has grown by around 50% in each decade in the post-independence period. The planning board of Delhi-NCR was constituted in 1985. The NCR currently consists of 14 districts of Haryana; eight districts of Uttar Pradesh; two districts of Rajasthan, and the entire NCT of Delhi. The current population of Delhi-NCR is estimated to be around 64 million.