Why do you think states are not given the power to coin their own money?

Nonetheless, certain elements are clear. First, Congress is granted the authority to "coin money," which authorizes Congress to coin money from precious metals such as gold and silver. Under the Articles of Confederation, the power to coin money was a concurrent power of Congress and the states. To create a more standardized monetary system and reduce the costs of running mints, the Constitution granted this power to Congress exclusively. The elimination of the states' power to coin money and the exclusive grant to Congress provoked controversy because the power to coin money was traditionally understood as a symbol of political sovereignty. Second, Congress is empowered to regulate the value of the coins struck domestically and to set the value of foreign coins. Under the Articles, Congress held the former power but not the latter. The Constitution gave both powers to Congress to encourage domestic and foreign commerce by preventing the states from attaching disparate valuations to circulating coins.

Beyond these simple issues, however, the scope of the federal government's powers under the Coinage Clause is unclear. In particular, although the Coinage Clause empowers Congress to coin money from precious metals, it is not clear whether the federal government could also issue paper money. Linguistic and conceptual usage during the Founding era distinguished between several different concepts: the power to "coin" specie money (i.e., money backed by gold or silver), the power to borrow money through the issuance of interest-bearing "notes," and the issuance of "Bills of Credit." Unlike coined money, whose value was inherent in the metal that composed the coin, and unlike "notes" that accrued interest, a bill of credit was non–interest-bearing paper money issued on the good credit of the United States with no tangible backing in precious metal.

macon. i believe thats the answer

sorry if im wrong.