Wis. Const. art. VIII, § 11

All funds collected by the state from any taxes or fees levied or imposed for the licensing of motor vehicle operators, for the titling, licensing, or registration of motor vehicles, for motor vehicle fuel, or for the use of roadways, highways, or bridges, and from taxes and fees levied or imposed for aircraft, airline property, or aviation fuel or for railroads or railroad property shall be deposited only into the transportation fund or with a trustee for the benefit of the department of transportation or the holders of transportation-related revenue bonds, except for collections from taxes or fees in existence on December 31, 2010, that were not being deposited in the transportation fund on that date. None of the funds collected or received by the state from any source and deposited into the transportation fund shall be lapsed, further transferred, or appropriated to any program that is not directly administered by the department of transportation in furtherance of the department’s responsibility for the planning, promotion, and protection of all transportation systems in the state except for programs for which there was an appropriation from the transportation fund on December 31, 2010. In this section, the term “motor vehicle” does not include any all-terrain vehicles, snowmobiles, or watercraft.