Usually depends on what "side of the city" you consider yourself "from".
Those from the Northside of the city, as well as those from the North suburbs are majority Cub fans. Wrigley Field is located on the North side.
Northsiders are usually stereotyped as yuppies and elitists and rich folk. Many of the North suburbs are white collar, wealthy, affluent areas. Pretty much every Chicago celebrity and pro athlete lives north of the city. The area around Wrigley Field is known as Wrigleyville and is one big party!
Southsiders, and those from many western parts of the city (some pretty rough areas) are predominantly White Sox fans for the exact opposite reasons above. US Cellular Field is located in an area that many folks are not comfortable travelling to, especially at night. The area around the White Sox stadium holds very little to do, you basically leave after the game, unlike the all night party that IS Wrigleyville. The Southside is regarded as a tough, blue collar, very ethnic area. Damned good people in my opinion!
Hell, I married a hot, ethnic Southside girl!
On a side note, the girls on the Southside are way more attractive in my opinion! Northside girls are often your Becky types - high maintenance, thin, expensive purse buying, chardonnay sipping chicks. Think Gwyneth Paltrow or Taylor Swift.
Southside girls? Tough, curse word using, ethnic, big curves, beer drinking, freaks who may be the toughest person in their household, despite having a male spouse or brothers living there. A lot of European and Latina girls on the Southside.
Sorry for getting sidetracked, but in case you ever go there, you need to know where "your type of girl" can be found, right?!
Hope I answered your question, my man!