Mo. Rev. Stat. § 137.101
The activities of nationally affiliated fraternal, benevolent, veteran or service organizations which promote good citizenship, humanitarian activities, or improve the physical, mental and moral condition of an indefinite number of people are purposes purely charitable within the meaning of subsection 1 of section 6 of article X of the constitution and local assessing authorities may exempt such portion of the real and personal property of such organizations as the assessing authority may determine is utilized in purposes purely charitable from the assessment, levy and collection of taxes.
(L. 1986 H.B. 1022, et al. § 1)
Effective 6-20-86