Minnesota constitution
Article XI
Section 9

The permanent university fund of this state may be loaned to or invested in the bonds of any county, school district, city or town of this state and in first mortgage loans secured upon improved and cultivated farm lands of this state, but no such investment or loan shall be made until approved by the board of investment; nor shall a loan or investment be made when the bonds to be issued or purchased would make the entire bonded indebtedness exceed 15 percent of the assessed valuation of the taxable property of the county, school district, city or town issuing the bonds; nor shall any farm loan or investment be made when the investment or loan would exceed 30 percent of the actual cash value of the farm land mortgaged to secure the investment; nor shall investments or loans be made at a lower rate of interest than two percent per annum nor for a shorter period than one year nor for a longer period than 30 years.