North Yankton can be explored through a glitch in GTA V
It seems that there is a glitch in GTA V that allows players to explore North Yankton, the town from the prologue section of the game.
The glitch allows players to jump back into North Yankton and explore without police attention via GTA Online.
It appears that the glitch was discovered after patch 1.07 was applied and can be accessed by helicopter if you get yourself invited to an invite only private session in GTA Online while playing through the single-player prologue.
The full video (above) detailing the steps you can take to jump in and explore North Yankton was created by CVG.