Final answer:
Federalism is the idea that power is shared between the national government and the states. Over US history, the power balance between the two levels of government has changed. Examples of events that caused shifts in the power balance include the period between 1819 and the 1860s, and the late 1870s.
Step-by-step explanation:
Federalism is the idea that power is shared between the national government and the states. The balance of power between the national and state governments has changed throughout US history. One event that caused a change in the power balance was the period between 1819 and the 1860s, when the national government sought to establish its role within the federal design, often provoking resistance from the states. Another event was the late 1870s, which ushered in a new phase of federalism known as dual federalism, where the states and national government exercised exclusive authority in distinctly delineated spheres of jurisdiction.