The department of revenue shall make an annual assessment of the property of all railroad companies, of all conservation and regulation companies, of all air carriers, and of all pipeline companies, within this state, for the purpose of levying and collecting taxes thereon, as provided in this subchapter.
Wis. Stat. § 76.01
The Department of Revenue's formula for determining the portion of an airline system's value subject to Wisconsin taxation does not offend the commerce clause, due process, or this section. Northwest Airlines, Inc. v. DOR, 77 Wis. 2d 152, 252 N.W.2d 337 (1977).