how do South Omaha's current street addresses correspond to pre-annexation adddresses?
They were renumbered to fit with the City of Omaha's numbering system. 5117 S 26th should tell you how many blocks south of Dodge that street address is. The Municipal Code (which dates back to 1980) includes information on numbering of the streets North & South of Dodge.
We have available online to Omaha Public Library cardholders the digitzed collection of Nebraska Sanborn maps. These were originally produced for fire insurnace purposes. If you look in the maps for Omaha, try the dates of 1901-1918, vol 3 for pre-annexation and 1901-Sept 1962 and vol. 3 for post annexation.
Hopefully you can view the two links below
pre-annexation, sheet 317, showing the area of N 26th between P & Q streets and the numbering of buidlings at the time.
post annexation, sheet 317, which shows the area of S 26th between P & Q streets and the numbering after annexation.
For further research if you can go to our local history collection at the W. Dale Clark Main Library on the 3rd floor, we have a colleciton of old street directories. You can look up by address in the street directories. Staff at the desk should be able to assist you with this.
We also have a book called The Streets of Omaha which can be borrowed and may have more information on changes in street numbering system.