After India became independent, its constituent units were classified into 4 distinct categories – Part A, Part B, Part C, Part D. Their composition is as follows
| Part A states | Former British provinces | An elected governor and state legislature | 9 states: Assam, Bihar, Bombay, East Punjab, Madhya Pradesh, Madras, Orissa, Uttar Pradesh, and West Bengal |
| Part B states | Former princely states or groups of Covenanting states | Rajpramukh (former princes) | 9 states: Hyderabad, Jammu and Kashmir, Madhya Bharat, Mysore, Patiala and East Punjab States Union (PEPSU), Rajasthan, Saurashtra, Travancore-Cochin, and Vindhya Pradesh |
| Part C | Former princely states and provinces | Chief commissioner | 10 states: Ajmer, Coorg, Cooch-Behar, Bhopal, Bilaspur, Delhi, Himachal Pradesh, Kutch, Manipur, and Tripura |
| Part D | Union Territory | Governor appointed by the Indian president | Andaman and Nicobar Islands |
1956: States Reorganization Act. Abolished the above 4-fold classification. Part A and Part B were merged. Part C territories – HP(including Bilaspur), Delhi, Manipur, and Tripura were made UTs and the rest merged with their adjoining states. Part D(Andaman & Nicobar Islands) was made a UT.
Total States: 14
UT Count: 6
1960: Bilingual state of Bombay was divided into Maharashtra and Gujrat.
Gujrat becomes the 15th State.
Total States: 15
UT Count: 6
1961: Dadra and Nagar Haveli, Portuguese colony till 1954 was converted into a UT by the 10th Constitutional Amendment Act. Dadra and Nagar Haveli becomes the 7th UT.
Total States: 15
UT Count: 7
1962: Goa, Daman and Diu were acquired from Portuguese by means of police action in 1961. Constituted as UT by the 12th Constitutional Amendment Act in 1962. They come 8th and 9th UT respectively.
Total States: 15
UT Count: 9
1962: State of Nagaland carved out from the state of Assam by 13th Constitutional Amendment Act in 1962. Nagaland becomes the 16th State.
Total States: 16
UT Count: 9
1962: 4 French establishments – Puducherry, Karaikal, Mahe and Yanam where handed over to India in 1954. Made a UT by the 14th Constitutional Amendment Act in 1962. Puducherry becomes the 10th UT.
Total States: 16
UT Count: 10
1966: Punjab was bifurcated to create Haryana. UT of Chandigargh was formed. Hilly Areas of Punjab were merged with Himachal Pradesh. Haryana becomes the 17th State. Chandigargh becomes the 11th UT.
Total States: 17
UT Count: 11
1970: HP elevated from the status of UT to the status of state. HP becomes the 18th State. The total UT count comes down to 10.
Total States: 18
UT Count: 10
1971: Political Map of NE underwent a Major Change. Manipur, Tripura and Meghayala elevated to the status of state. The total State-count becomes 21.
Total States: 21
UT Count: 10
1975: Referendum held in Sikkim and Sikkim became an integral part of India. 36th Constitutional Amendment made it the 22nd full-fledged state.
Total States: 22
UT Count: 10
1986: Mizoram and Arunachal Pradesh elevated from status of UT to the status of state. The total State-count becomes 24. The total UT-count comes down to 8.
Total States: 24
UT Count: 8
1987: Goa elevated from status of UT to the status of state. Becomes the 25th State. The total UT count comes down to 7.
Total States: 25
UT Count: 7
1991: Delhi becomes the National Capital Territory of Delhi.
2000: Chhattisgargh(from MP), Uttarakhand(from UP) and Jharkhand(from Bihar) carved out to form independent states. The total State-count is 28.
Total States: 28
UT Count: 7
2014: Andhra Pradesh bifurcated to form Telangana. Becomes the 29th State.
Total States: 29
UT Count: 7
