sanguine - SAN-gwin - robust, upbeat, optimistic (also ruddy complexioned)
Example: "Isn't it amazing, regardless our everyday political attitudes, how sanguine we become on the 4th of July."
As a starter: and as a former teacher in English, I hope to add to reader's vocabulary by presenting a word a day in simple terms that anyone can understand - from current use in publications, radio,TV, etc. Remember: use a new word three times in a day and it's yours forever!