Why are soda cans cylindrical and milk cartons rectangular?

Soda cans are cylindrical primarily for structural integrity and efficient manufacturing processes, allowing them to withstand pressure from carbonation while minimizing material usage. Their shape also facilitates easy stacking and storage. In contrast, milk cartons are rectangular, which optimizes space efficiency in both production and transportation, making them easy to pack and store in refrigerators. The rectangular design also allows for a more effective pouring mechanism.