Los Angeles was extensively researched for the game. The team organised field research trips with tour guides and architectural historians, and captured around 250,000 photographs and many hours of video footage. Houser said, "We spoke to FBI agents that have been undercover, experts in the Mafia, street gangsters who know the slangwe even went to see a proper prison". He considered the open world's research and creation the most challenging aspects of the game's production. Google Maps and Street View projections of Los Angeles were used by the team to help design Los Santos' road networks. The team studied virtual globe models, census data and documentaries to reproduce the city's geographical and demographic spread. The team opted to condense the city's spread into an area players could comfortably traverse to capture "the essence of what's really there in a city, but in a far smaller area", according to Houser. The New Yorker Sam Sweet opined that the "exhaustive field work ... wasn't conducted to document a living space. Rather, it was collected to create an extremely realistic version of a Los Angeles that doesn't actually exist". Garbut noted that Los Angeles was used merely as a starting point and that the team were not "dictated by reality" while building Los Santos.
