Joseph & Mary went to Bethlehem because it was the "City of" this king & Joseph came from his lineage
[DOC] [TLE] LUKE 2:4 KJV "And Joseph also went up from ... - King James Bible [PAR] Luke 2:4 KJV: And Joseph also went up from Galilee, out of the city of ... David, 
which is called Bethlehem; (because he was of the house and lineage of David:) 
... And it came to pass in those days, that there went out a decree from Caesar ... 
was of the house and lineage of David:)To be taxed with Mary his espoused wife,
... [DOC] [TLE] Saint Joseph - Wikipedia [PAR] Joseph is a figure in the Gospels, the husband of Mary, mother of Jesus, and is 
venerated as ... Each contains a genealogy of Jesus showing ancestry from king 
David, but ...