SoNo in Atlanta means South of North Avenue:

Following History by Jennifer Ball, Vice President, Central Atlanta Progress, Inc./Atlanta Downtown Improvement District, Inc.:

By To the best of my knowledge, the first instance of the use SoNo was by the Midtown Alliance during their Blueprint planning process which dates to 1999-2000.  I became aware of their short-hand term when CAP was working on the Imagine Downtown plan in 2003.  The term was used during the Imagine Downtown planning process to describe the subarea of the plan generally bounded by North Avenue, Central Park Place and Ralph McGill/Boulevard/I-75/85 as a compromise to the conflict of is it Midtown or is it Downtown.

 The use of Central Park Place as the eastern boundary, as opposed to Courtland or Piedmont, derived from a zoning update process that merged the old SPI-2 into the same district as SPI-1 between 2003 and 2007.  The SPI-2 district had only extended east to Courtland Street, but through the discussion of future land use and development, it was determined that the SPI level of design control needed to extend east.  

 In 2005, the wayfinding signage program used the acronym as a tool to direct to those destinations in the area – notably, at the time Crawford Long Hospital (not yet Emory Midtown) and the Civic Center.  The wayfinding signage program intentionally did not use strict district boundary maps on signs; however, for the purpose of grouping destinations the district was essentially the area described above.