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    ACCESSION NUMBER:		0001140361-18-018485
    CONFORMED SUBMISSION TYPE:	DEF 14A
    PUBLIC DOCUMENT COUNT:		26
    CONFORMED PERIOD OF REPORT:	20180523
    FILED AS OF DATE:		20180413
    DATE AS OF CHANGE:		20180413
    EFFECTIVENESS DATE:		20180413

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			COLUMBIA BANKING SYSTEM INC
    		CENTRAL INDEX KEY:			0000887343
    		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
    		IRS NUMBER:				911422237
    		STATE OF INCORPORATION:			WA
    		FISCAL YEAR END:			1231

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    		FORM TYPE:		DEF 14A
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	000-20288
    		FILM NUMBER:		18753809

    	BUSINESS ADDRESS:
    		STREET 1:		1301 A STREET
    		CITY:			TACOMA
    		STATE:			WA
    		ZIP:			98402
    		BUSINESS PHONE:		2533051900

    	MAIL ADDRESS:
    		STREET 1:		1301 A STREET
    		CITY:			TACOMA
    		STATE:			WA
    		ZIP:			98402
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