Question in the title. Did some searching but no luck finding the answer.
May I also ask why the change from street to avenue?
TIA,
Dave…
Found this a few google pages down from where I initially stopped:
Father Damen was a huge figure in the history of Chicago Catholic Church. I believe Robey was changed to Damen years after Father Damen died.
"…Father Damen thought big. He envisioned the erection of a large parish Church, primary and secondary schools, and a college as part of this new venture. This was a day when few parishes had schools, and Catholic colleges were a rarity. Shrewdly, but respectfully, resisting Archbishop O’Regan’s proposed location for the new parish, the Dutchman purchased property on what is now the “Near West Side” in Spring of 1857. The area was not well inhabited. In fact, his critics asked how he could build and support a parish without any parishioners. But Father Damen had judiciously forecast the demographics of the growing Midwestern metropolis, and replied, with a characteristic confidence, “I shall not go to the people; I shall draw the people to me…”’
"…The City of Chicago memorialized its Jesuit apostle in 1927, when it renamed Robey Street, “Damen Avenue…”
Father Arnold Damen, Chicago’s Jesuit Apostle — Catholicism.org - Saint Benedict Center, The Slaves of the Immaculate Heart of Mary
“…explosive urban growth, annexation, and the popular political favor of honorary street naming resulted in multiple streets of the same name and streets known by several different names. In 1901, building superintendent Edward P. Brennan confronted the confused state of affairs. He suggested that Chicago be ordered as a large grid with a uniform street numbering system, and proposed State and Madison Streets as the city’s primary north-south and east-west axes. In 1908, the “Brennan” system was officially adopted by the city council and became the basis of modern Chicago’s street naming system…”
“…Of the more than a thousand streets within Chicago’s city limits today, the greatest number—more than 170—bear the names of real-estate developers. English towns and Chicago’s former mayors and aldermen have provided the next most popular sources of names…”
Street Naming
According to my 1988 copy of “Streetwise Chicago” by Don Hayner and Tom McNamee:
"Father Damen managed a near-miracle during the Chicago Fire of 1871. He was in New York City the day the great fire struck, and he fell his knees and prayed. He vowed that, should God spare his parish church from the fire’s flames, a light would be kept burning forever in the church.
His prayeres were answered. The fire began within blocks of the church, but the southwest wind turned the flames toward downtown. And seven lights, recently electric bulbs, have burned for more than one hundred years before the image of Our Lady of Perpetual Help in Holy Family Church at Roosevelt and May streets.
Given clout like that, the City Council in 1927 wisely named a street for him."
Cecil is going to use this question in a column. You’ve got the gist of the answer, but there’s an important detail that needs to be told.
And here’s the column, as Ed promised: http://chicago.straightdope.com/sdc20091231.php
Congrats, daveg, on being one of the lucky few to have your question addressed by the Master Hisself!
The “Milwaukee Blank Road” should, indeed have been “Plank.” The full name of the road was “Chicago-Milwaukee Plank Road.” This can be ascertained from many old documents of record in the Cook Country Recorder of Deeds.
I feel honored. I think. 
Connecting another Damen dot…
There is a Damen Hall at the Loyola Lake Shore campus. I think it’s scheduled to come down this year.
I wonder how many people associate this name with the 2000 west street name. I’ll admit I didn’t.
Thanks for this great site. I’m learning.