For purposes of this section and section 273.135, "municipality" means any city, however organized, or town, and the applicable assessment date is the date as of which property is listed and assessed for the tax in question.

1. (1) it is a municipality in which the assessed valuation of unmined iron ore on May 1, 1941, was not less than 40 percent of the assessed valuation of all real property; or
2. (2) it is a municipality in which, on January 1, 1977 or the applicable assessment date, there is a taconite concentrating plant or where taconite is mined or quarried or where there is located an electric generating plant which qualifies as a taconite facility.

For the purposes of section 273.135 "tax relief area" means the geographic area contained, within the boundaries of a school district which contains a municipality which meets the following qualifications: