The Metropolitan Cross is always carried in procession before a metropolitan archbishop and dates back to the midthirteenth century. The origin of the second [higher and smaller bar of the cross] lies in the representation of the small board, or plaque, on which was hung the inscription I.N.R.I., an abbreviation that stands for the Latin phrase Iesus Nasarenus Rex Iudaeonum (Jesus of Nazareth, King of the Jews).*
The four images in each corner of the metropolitan cross represent (starting on the top left and moving clockwise) (1) rural life, (2) urban centers, (3) the sacramental water of baptism as well as the Mississippi River, and (4) service to others.
Official high resolution logo files can be found online at DBQArch.org/Offices/Communications.
* The Church Visible: The Ceremonial Life and Protocol of the Roman Catholic Church by James-Charles Noonan, Jr.