Symbols are small pictures that stand for different features on a map. A symbol is often drawn to look like what it represents. For example, a triangular shape is often used to denote a mountain. A desert is often shown by a group of dots that might look a little bit like sand. A forest could have little shapes that look like trees. A railroad can be shown as a line with bars drawn across it, like a train’s track.
All the symbols for a map are often grouped together in a MAP KEY for reference. Sometimes the MAP KEY is a box shape where the symbols are arranged. Sometimes the symbols are displayed in a more freeform manner, without a box around them.
I believe that Mexico would not end up owning California because USA's ambition for manifest destiny was way to strong. The USA would have found a way to take back California because they were so determined to own land from coast to coast. Thomas even went against his own morals to purchase the Louisiana Territory. That's how strongly the states wanted that land.
