Okay, if this went down how he described it, there would have been utter chaos; have you been in the Denver airport around Thanksgiving? Everyone had to return to their ancestral home, and by ancestral - that means retracing your family tree to 1000 years ago. Imagine an American dealing with that decree. Good luck with that.
In Matthew, Mary and Joseph appear to live in Bethlehem and did not need to travel there prior to Jesus' birth. The author of Luke had to get Mary to Bethlehem to have her baby in order to have what he believed was prophetic fulfillment of Micah 5:1. For this he devised a census using as his basis an actual census that took place around the time when Jesus was born.
The three empire-wide censuses, actually. There was one in 28 B.C., 8 B.C., and 14 A.D. In all probability the one in 8 B.C. is the one the Luke mentions in the Christmas story. Even though scholarship normally dates Christ's birth between 4 and 7 B.C., the 8 B.C. census fits because in all likelihood it would have taken several years for the bureaucracy of the census to reach Palestine.
What Luke describes has the makings of a chaotic situation of unprecedented magnitude. The people involved would have had to travel throughout the length and breath of the Roman Empire, clogging the roads and disrupting the smooth running of the imperial system in every province of the Empire. In the course of their journey, they would be traveling, for the most part, over extremely poor roads once they left the major Roman highways. Available services to travelers would be strained to the breaking point. Certainly in the eastern provinces, of which Judea was part, such a census would present a serious military danger, for the Parthians, then Rome's strongest antagonist in the area, would have had an excellent opportunity to attack. Roman troops on the march would find it extremely difficult to compete with the tremendous mass of civilians on their way to or from registration. It is hard to imagine the Romans so incompetent or unrealistic as to throw the entire Empire into such a chaotic state by carrying out the census described by the evangelist.
It is unusual that an event of this magnitude should go unnoticed. Yet no contemporary writer mentions this disruptive census or the turmoil it would have engendered. Indeed, if this census took place in Judea it is strange that Josephus never mentioned it in any of his writings. It is obvious that Luke introduced the tale to explain still another legendary tale, that is, how it came about that Joseph and Mary went to Bethlehem at this time.
Some scholars have scoffed at the notion that people in faraway Palestine (such as Joseph and Mary) would have had to travel to their ancestral birth place for a census. But we have evidence to show that such traveling was indeed done with a Roman census, in Egypt.
A Roman census document, dated 104 A.D., has been discovered in Egypt, in which citizens were specifically commanded to return to their original homes for the census. Another census document from 119 A.D. has been found in which an Egyptian man identifies himself by giving (1) his name and the names of his father, mother, and grandfather; (2) his original village; (3) his age and profession; (4) a scar above his left eyebrow; (5) his wife's name and age, his wife's father's name; (6) his son's name and age; (6) the names of other relatives living with him. The document is signed by the village registrar and three official witnesses. This latter document is of special interest, because it gives us an idea of the kind of information that Joseph and Mary would have had to provide for the census.
Roman Census Taker: "Any children?"
Mary: "Give me a minute."
Roman Census Taker: "Who's the father?"
Mary: "Uh, that's a long story."