The only information I was ever able to find was on lofts BEING built. They are going to be in the old Pierce Moving and Storage building. If you go to United Real Estate's website (a few posts down) there is a teeny bit of info under their commercial properties. Kevin Archer is the realtor that you need to contact to get more information on buying them.
There definitely is an exciting new Urban Loft Condo project underway right now in Sioux City, IA. If you would like more information, go to http://www.unitedrealestatesolutions.com and type urban loft condo in the keyword search. Hope you find what you're looking for!
There are most likely lofts in your downtown, I am a Realtor in Alta and Storm Lake, just east of you and we have both lofts and condo's being developed in the downtown areas. In fact, if you are interested in seeing how one of these downtown areas becomes a living area check out the blog below. Several Sioux City agents you may want to contact are Rita Mosher, Katherine Schwedler and Jim Horne. Contact me if you need more information.
Your question seems to be about the existence of lofts in downtown Sioux City.
Although I am not from your area, I do know that in many smaller cities ( like Roanoke, my hometown ) there is a good deal of excitement about the redevelopment of "downtown living spaces" ( lofts, condos, etc. ). I would contact a Realtor who serves your area to see if this trend applies to Sioux City as well.