Relationship between the states and the national government
The relationship between the states and the national government can be strained at times because of the issue of Unfunded Mandates; these are instructions/orders/expectations imposed on state governments without the necessary funds to meet those expectations. On the other hand, states receive monies from the national government in the form of grants for various projects. The national government has and will always have more money than state governments in part because the national government has more revenue sources and streams. For example, every working American pays federal income taxes depending on their earnings and the monies that come from these taxes alone are huge. Puerto Rico is an exception. With regard to the states, seven of them - Alaska, New Hampshire, Tennessee, Texas, Wyoming, South Dakota, and Washington don't require their citizens to pay state income taxes, which shrinks their potential revenue stream.
Now, should states' ability to receive grants and other financial assistance from the national government hinge on them complying with federal Unfunded Mandates?