Final answer:
The colonists were mad over the Proclamation Line of 1763 because it prevented them from settling west of the Appalachian Mountains. They viewed it as an infringement on their right to westward expansion and as an act of tyranny by the British Crown.
Step-by-step explanation:
The colonists were mad over the Proclamation Line of 1763 because it forbade them from settling west of a line drawn along the Appalachian Mountains. This meant that some colonists who had already received land grants west of the Appalachians were unable to settle on their land. The colonists viewed this edict as an infringement on their right to westward expansion and saw it as a form of tyranny by the British Crown.