You said, "True, Ur was in what is today southern Iraq." This is false! Try looking up the Ur of Khaldis , near Harran, which was in Northern Mesopotamia [Syria] [Sur] [Surie]. This is where Abram was from.
I did find an article by an anthropologist at Utah State University who claims by elaborate stretches that the Ur of Abram's origins had to be in northern Mesopotamia. However, to gain this claim, he resorted to the arbitrary divisions of the Old Testament text as claimed by "Higher Criticism" and assertions that contrary possibilities cannot be. In other words, he approached the Scriptures as non-inspired, fragmented works of men who did not know nearly as much as today's intellectuals and from this basis derived his conclusion.
"And Haran died before his father Terah in his native land, in Ur of the Chaldeans. Then Abram and Nahor took wives: the name of Abram's wife was Sarai, and the name of Nahor's wife, Milcah, the daughter of Haran the father of Milcah and the father of Iscah. But Sarai was barren; she had no child. And Terah took his son Abram and his grandson Lot, the son of Haran, and his daughter-in-law Sarai, his son Abram's wife, and they went out with them from Ur of the Chaldeans to go to the land of Canaan; and they came to Haran and dwelt there. So the days of Terah were two hundred and five years, and Terah died in Haran" (Genesis 11:28-32).
Even before digging into the details, the passage cited above tells us that Terah and his family, including Abram, left a place called "Ur of the Chaldeans" to head toward Canaan. However, when they reach Haran, they stopped and settled there. Thus, the contention that Ur was in the area of Haran would not match the biblical description of Abram's journey.
The phrase "Ur of the Chaldeans" is from the Hebrew ur kasdim. You will note that kasdim is nowhere close to the spelling of khaldis in transliterated Hebrew or in the actual Hebrew. The word kasdim is consistently applied by the Bible to the people located in the southern portion of Mesopotamia near the Persian Gulf. The kingdom of Babylonia was ruled by Chaldeans (kasdim in the plural and kasday in the singular -- Hebrew doesn't use an "s" to make a plural as the English language does). "In the third year of the reign of Jehoiakim king of Judah, Nebuchadnezzar king of Babylon came to Jerusalem and besieged it. And the Lord gave Jehoiakim king of Judah into his hand, with some of the articles of the house of God, which he carried into the land of Shinar to the house of his god; and he brought the articles into the treasure house of his god. Then the king instructed Ashpenaz, the master of his eunuchs, to bring some of the children of Israel and some of the king's descendants and some of the nobles, young men in whom there was no blemish, but good-looking, gifted in all wisdom, possessing knowledge and quick to understand, who had ability to serve in the king's palace, and whom they might teach the language and literature of the Chaldeans" (Daniel 1:1-4).
According the Complete Biblical Library Hebrew - English Dictionary, "The Chaldeans first appeared in the ninth century, as a tribal confederation in the extreme southern part of Mesopotamia, known as Sealand, in an area known as Sumer. The tribes immediately made allies of the Babylonians and Elamites (who lived just east of Babylon), and often were in conflict with their Assyrian overlords. Assyrian records claim that over 200,000 Chaldeans were deported and resettled throughout the empire (suffering the same fate as Samaria and the northern tribes of Israel). Five tribes were attested in the region. Some were quickly 'babylonianized,' taking on Babylonian names among the elite and becoming involved in Babylonian politics. Virtually no cultural remnants of Chaldeans are discernible, given their ready acceptance of Babylonian culture, art forms and religion."
Therefore, the article proves to be accurate.