Luke 2:1-5

At that time, Augustus Caesar sent an order that all people in the countries under Roman rule must list their names in a register. This was the first registration; it was taken while Quirinius was governor of Syria. And all went to their own towns to be registered. So Joseph left Nazareth, a town in Galilee, and went to the town of Bethlehem in Judea, known as the town of David. Joseph went there because he was from the family of David. Joseph registered with Mary, to whom he was engaged and who was now pregnant.