Standard time zones can be defined by geometrically subdividing the Earth's spheroid into 24 lines (wedge-shaped sections), bordered by meridians each 15° of longitude apart. The local time in neighbouring zones is then exactly one hour different. However, political and geographical practicalities can result in irregularly-shaped zones that follow political boundaries or that change their time seasonally (as with daylight saving time), as well as being subject to occasional redefinition as political conditions change.
In all Argentina, the time zone is GTM -3.
