The St. Croix River forms part of the boundary between Minnesota and which state?

The St. Croix River serves as a natural boundary between Minnesota and Wisconsin. This river flows from the headwaters in northwestern Wisconsin and travels southward, ultimately joining the Mississippi River. The St. Croix is a significant geographical feature that historically played a vital role in the development and settlement of both states. Its banks are known for their natural beauty and recreational opportunities, making it an important resource for residents of both Minnesota and Wisconsin.

The other states mentioned—Idaho, Iowa, and Illinois—do not border the St. Croix River, making them not relevant to the question regarding which state shares a boundary with Minnesota along this river.