Mo. Rev. Stat. § 400.9-301: Law governing perfection and priority of security interests.

Except as otherwise provided in sections 400.9-303 through 400.9-306, the following rules determine the law governing perfection, the effect of perfection or nonperfection, and the priority of a security interest in collateral:

(1) Except as otherwise provided in this section, while a debtor is located in a jurisdiction, the local law of that jurisdiction governs perfection, the effect of perfection or nonperfection, and the priority of a security interest in collateral;

(2) While collateral is located in a jurisdiction, the local law of that jurisdiction governs perfection, the effect of perfection or nonperfection, and the priority of a possessory security interest in that collateral;

(3) Except as otherwise provided in paragraph (4), while negotiable documents, goods, instruments, money, or tangible chattel paper is located in a jurisdiction, the local law of that jurisdiction governs:

(A) Perfection of a security interest in the goods by filing a fixture filing;

(B) Perfection of a security interest in timber to be cut; and

(C) The effect of perfection or nonperfection and the priority of a nonpossessory security interest in the collateral;

(4) The local law of the jurisdiction in which the wellhead or minehead is located governs perfection, the effect of perfection or nonperfection, and the priority of a security interest in as-extracted collateral.