| Answer | Crossword Clue |
|---|---|
| ARBOR | ... Day, first observed in 1872. |
| THANKSGIVING | National day of gratitude, first observed by the Pilgrims in 1621 |
| POSITRON | Antiparticle first observed in 1929 |
| NEPTUNE | It was first observed in 1846 |
| UNO | First album in a Green Day trilogy |
| CALENDS | First day of each month, in ancient Rome. |
| CALENDS | First day of the month, in ancient Rome |
| OCANADA | Song first played on Saint-Jean-Baptiste Day in 1880 |
