Congress has the power to admit new states into the United States. The last state admitted to the country was Hawaii in 1959.
Congress is also granted power over the United States territories, like Puerto Rico. Every state that is admitted into the union of the United States since 1796, when Tennessee was made a state, is done on the understanding that the new state will be equal to all other states. No state will have special consideration for laws or be made exempt from federal laws and requirements of statehood. This also prevents the government from requiring special conditions or any type of tribute from the areas to obtain statehood.