Why union territories are formed?

The union territories have been created for a variety of reasons. These are mentioned below:

• Political and administrative considerations – Delhi and Chandigarh. 
• Cultural distinctiveness – Puducherry, Dadra and Nagar Haveli, and Daman and Diu. 
• Strategic Importance – Andaman and Nicobar Islands and Lakshadweep. 
• Special treatment and care of the backward and tribal people – Mizoram, Manipur, Tripura, and Arunachal Pradesh which later became states. 

Though all these Union territories belong to one category, there are some differences in the actual system of administration as between the several Union Territories owing to the provisions of the Constitution as well as of Acts of Parliament which have been made in pursuance of the Constitutional provisions. 

Further Reading:

• Union Territories 
• Difference between State and Union Territory