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<?xml version="1.0" encoding="windows-1252"?> |
<ownershipDocument> |
| <schemaVersion> X0508 </schemaVersion> |
| <documentType> 4 </documentType> |
| <periodOfReport> 2024-02-14 </periodOfReport> |
| <issuer> |
| | <issuerCik> 0000066740 </issuerCik> |
| | <issuerName> 3M CO </issuerName> |
| | <issuerTradingSymbol> MMM </issuerTradingSymbol> |
| | </issuer> |
| <reportingOwner> |
| | <reportingOwnerId> |
| | | <rptOwnerCik> 0001890011 </rptOwnerCik> |
| | | <rptOwnerName> Chavez Rodriguez Beatriz Karina </rptOwnerName> |
| | | </reportingOwnerId> |
| | <reportingOwnerAddress> |
| | | <rptOwnerStreet1> 3M CENTER </rptOwnerStreet1> |
| | | <rptOwnerStreet2></rptOwnerStreet2> |
| | | <rptOwnerCity> ST. PAUL </rptOwnerCity> |
| | | <rptOwnerState> MN </rptOwnerState> |
| | | <rptOwnerZipCode> 55144 </rptOwnerZipCode> |
| | | <rptOwnerStateDescription></rptOwnerStateDescription> |
| | | </reportingOwnerAddress> |
| | <reportingOwnerRelationship> |
| | | <isOfficer> 1 </isOfficer> |
| | | <officerTitle> Group President </officerTitle> |
| | | </reportingOwnerRelationship> |
| | </reportingOwner> |
| <aff10b5One> 0 </aff10b5One> |
| <nonDerivativeTable> |
| | <nonDerivativeTransaction> |
| | | <securityTitle> |
| <value> Common Stock </value> |
| </securityTitle> |
| | | <transactionDate> |
| <value> 2024-02-14 </value> |
| </transactionDate> |
| | | <transactionCoding> |
| <transactionFormType> 4 </transactionFormType> |
| <transactionCode> S </transactionCode> |
| <equitySwapInvolved> 0 </equitySwapInvolved> |
| </transactionCoding> |
| | | <transactionTimeliness></transactionTimeliness> |
| | | <transactionAmounts> |
| <transactionShares> |
| <value> 426 </value> |
| </transactionShares> |
| <transactionPricePerShare> |
| <value> 92.3231 </value> |
| </transactionPricePerShare> |
| <transactionAcquiredDisposedCode> |
| <value> D </value> |
| </transactionAcquiredDisposedCode> |
| </transactionAmounts> |
| | | <postTransactionAmounts> |
| <sharesOwnedFollowingTransaction> |
| <value> 3965.9347 </value> |
| </sharesOwnedFollowingTransaction> |
| </postTransactionAmounts> |
| | | <ownershipNature> |
| <directOrIndirectOwnership> |
| <value> D </value> |
| </directOrIndirectOwnership> |
| </ownershipNature> |
| | | </nonDerivativeTransaction> |
| | <nonDerivativeHolding> |
| | | <securityTitle> |
| <value> Common Stock </value> |
| </securityTitle> |
| | | <postTransactionAmounts> |
| <sharesOwnedFollowingTransaction> |
| <value> 2209.385 </value> |
| </sharesOwnedFollowingTransaction> |
| </postTransactionAmounts> |
| | | <ownershipNature> |
| <directOrIndirectOwnership> |
| <value> D </value> |
| </directOrIndirectOwnership> |
| </ownershipNature> |
| | | </nonDerivativeHolding> |
| | </nonDerivativeTable> |
| <footnotes></footnotes> |
| <ownerSignature> |
| | <signatureName> Patricia L. Meagher, attorney-in-fact for Beatriz Karina Chavez Rodriguez </signatureName> |
| | <signatureDate> 2024-02-15 </signatureDate> |
| | </ownerSignature> |
| </ownershipDocument> |