States' rights are the rights and powers reserved for individual states. Any rights not specifically reserved for the federal government are considered state rights or powers.
States' rights are recognized in the Tenth Amendment, and include looking after the health, education and general welfare of the citizens. Some specific examples of exclusive state rights include the rights to issue licenses, conduct elections, ratify changes to the federal Constitution and establish local governments. These rights are not regulated by the federal government and are the sole responsibility of state governments.
Some powers are shared between the state and federal governments, such as the right to collect taxes, build roads and charter banks. These powers can be overseen by the national or state government, or both jointly. Powers that are exclusive to the national government and not the states include printing money, declaring war and establishing post offices.
The states also have the ability to create laws independently of the federal government that may clash with federal law. For example, marijuana is still illegal at the federal level, but it is legal in some states for various purposes. The issue of states' rights or powers and how they worked with the federal government was also a core component of the Civil War.