It has been published in the Washington Post on December the 31st 1995. It's sad to say it, but Watterson retired... But the last strip is full of optimism and let a possibility to restart the cartoon...
http://calvinethobbes.free.fr/english/c_der.html
I am sad summer is over. I am glad the kids are returning and starting school. I am reminded of the last Calvin and Hobbs comic. It was published a few years ago now but it still follows me through my life.
The script reads;
C: Wow It really snowed last night! Isn't it wonderful?
H: Everything familiar has disappeared! The world looks brand new!
C: A new year, A fresh clean start!
H: It's like having a big white sheet of paper to draw on!
C: A day full of possibilities!
C: It's a magical world, Hobbes o'l buddy...
C: ...Lets go exploring!
They are starting fresh, I am starting fresh, I am happy we have a new beginning