Foundation Day of Indian States & Union Territories
| Date | State / Union Territory | Status & Historical Significance |
| Jan. 21 | Manipur, Meghalaya, Tripura | Attained full statehood in 1972 under the North-Eastern Areas (Reorganisation) Act. |
| Jan. 24 | Uttar Pradesh | Observed as UP Diwas (renamed from United Provinces in 1950). |
| Jan. 25 | Himachal Pradesh | Statehood Day (achieved full statehood in 1971). |
| Jan. 26 | Dadra & Nagar Haveli and Daman & Diu | Merged UT: Combined into a single Union Territory on Jan 26, 2020. |
| Feb. 20 | Arunachal Pradesh, Mizoram | Both attained statehood on this day in 1987. |
| Mar. 22 | Bihar | Celebrated as Bihar Diwas (carved out from Bengal in 1912). |
| Mar. 30 | Rajasthan | Celebrated as Rajasthan Day. |
| Apr. 1 | Odisha | Celebrated as Utkal Dibasa (formed in 1936; formerly spelled Orissa). |
| Apr. 14 | Tamil Nadu | Tamil Nadu Day (also commemorated on Nov 1 following the 1956 reorganisation). |
| Apr. 15 | Himachal Pradesh | Himachal Day (marking its creation as a province in 1948). |
| May 1 | Gujarat, Maharashtra | Formed in 1960 under the Bombay Reorganisation Act. |
| May 16 | Sikkim | Became the 22nd Indian state in 1975 via the 36th Constitutional Amendment. |
| May 30 | Goa | Statehood Day: Goa became a full state in 1987. |
| June 2 | Telangana | Telangana Formation Day: Carved out of Andhra Pradesh in 2014. |
| June 20 | West Bengal | Celebrated as Paschim Banga Dibas (marking the 1947 partition resolution). |
| Oct. 31 | Jammu & Kashmir, Ladakh | Updated: Reorganised into two separate Union Territories on Oct 31, 2019. |
| Nov. 1 | States: Andhra Pradesh, Chhattisgarh, Haryana, Karnataka, Kerala, Madhya Pradesh, Punjab UTs: Andaman & Nicobar Islands, Chandigarh, Delhi (NCT), Lakshadweep, Puducherry | Reorganisation Day: Major alignment day under the States Reorganisation Act of 1956 & 1966. |
| Nov. 9 | Uttarakhand | Uttarakhand Day (carved out of UP in 2000; formerly Uttaranchal). |
| Nov. 15 | Jharkhand | Celebrated as Jharkhand Diwas (carved out of Bihar in 2000). |
| Dec. 1 | Nagaland | Nagaland Statehood Day (Official statehood granted on Dec 1, 1963). |
| Dec. 2 | Assam | Celebrated as Asom Divas (commemorating the Ahom kingdom rule). |
| Dec. 19 | Goa | Goa Liberation Day: Marks liberation from Portuguese rule in 1961. |