at south side vs in south side

Some examples from the web:

• Do you know Dominic and Sarah at South Side?
• I'm at the south side with my men.
• We followed some tired tracks to the canyon edge at the south side of town.
• Medic, we have a major accident at the south side of the building.
• See you at 4507 B South Side Layer.
• Command unit of radio relay at both south side and north side...
• He's on the south side.
• All units, converge on Skyway platform, south side of park.
• I used to work for this guy on the south side...
• (Radio chatter) Sniper on the south side.
• Then the south side, by the dumpsters.
• This is the south side of the warehouse.
• All clear on the south side.
• It shows all eight cameras from both the north and south sides.
• I got eyes on security, south side of the building.
• They're running eastbound on the south side.
• He works mainly on the south side.
• I want you to access the south side.
• I grew up on the south side of Chicago.
• Fourth floor, south side, second unit down.

Some examples from the web:

• Tonya doesn't own the land in the South side hills.
• Homeless families in the south side are using boarded-up houses for shelter.
• Another functional work, it's in the south side of Chicago for a subway station.
• I'll meet you in the south side of the building in ten minutes.
• It looks like we've got something here in the South side.
• Chris Lawrence, 25, gunned down in an FBI raid of an apartment in the south side of Chicago a year and a half ago.
• And I was taking care of people who were dying and their families in the South Side of Chicago.
• He's on the south side.
• All units, converge on Skyway platform, south side of park.
• I used to work for this guy on the south side...
• (Radio chatter) Sniper on the south side.
• Then the south side, by the dumpsters.
• This is the south side of the warehouse.
• All clear on the south side.
• It shows all eight cameras from both the north and south sides.
• I got eyes on security, south side of the building.
• They're running eastbound on the south side.
• He works mainly on the south side.
• I want you to access the south side.
• I grew up on the south side of Chicago.