To become a state, people in each territory write a constitution

In some cases, an entire territory became a state; in others, some part of a territory became a state. ... Upon acceptance of that constitution, by the people of the territory and then by Congress, Congress would adopt by simple majority vote a joint resolution granting statehood.

Explanation:

So yes, to become a state, people in each territory write a constitution.

I believe it is because the west had access to gold mines from colonies. China had and rapidly increasing demand for gold because the government input a new law called the Single Whip Law. The placement of the law meant that everyone had to pay their taxes to the chines government as one single payment of gold.