Greeting the people of Meghalaya, Modi said: "My dear sisters and brothers of Meghalaya, my greetings on your statehood day. I extend my best wishes for Meghalaya's development journey."
The prime minister also said that he was "committed to leaving no stone unturned to ensure that the dreams of Meghalaya's youngsters are fulfilled and they get opportunities to shine".
Extending warm greetings to the citizens of Tripura, Modi said: "I have very fond memories of my visit to Tripura in December last year. I will always remember your warm nature and the excellent hospitality."
With regard to the people of Manipur, the prime minister said: "I hope Manipur scales newer heights of progress in the years to come."
"I can never forget the enthusiasm with which I was welcomed into Manipur during my recent visit. I was fortunate to join the Sangai Festival, which showcases Manipur's rich culture."
"We are very proud of the hard work and dynamism of the people of Manipur. We are committed to doing everything possible that will give an impetus to Manipur's all-round development," he said.
Modi tweeted his greetings in the local languages.
The erstwhile princely states of Tripura and Manipur were merged with India in October 1949 and became full-fledged states Jan 21, 1972.
Meghalaya was a part of Assam before it was carved out as a full-fledged state under the North Eastern Region (Re-Organisation) Act, 1971.