    <SEC-DOCUMENT>0001193125-21-346812-index.html : 20211202
    <SEC-HEADER>0001193125-21-346812.hdr.sgml : 20211202
    <ACCEPTANCE-DATETIME>20211202171252
    ACCESSION NUMBER:		0001193125-21-346812
    CONFORMED SUBMISSION TYPE:	S-4/A
    PUBLIC DOCUMENT COUNT:		17
    FILED AS OF DATE:		20211202
    DATE AS OF CHANGE:		20211202

    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

    	FILING VALUES:
    		FORM TYPE:		S-4/A
    		SEC ACT:		1933 Act
    		SEC FILE NUMBER:	333-261281
    		FILM NUMBER:		211467713

    	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

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	COLUMBIA BANKING SYSTEM INC
    		DATE OF NAME CHANGE:	19930328
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>S-4/A
    <SEQUENCE>1
    <FILENAME>d261205ds4a.htm
    <DESCRIPTION>S-4/A
    <TEXT>
    Document 1 - file: d261205ds4a.htm

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    <DOCUMENT>
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    <SEQUENCE>2
    <FILENAME>d261205dex51.htm
    <DESCRIPTION>EX-5.1
    <TEXT>
    Document 2 - file: d261205dex51.htm

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    <DOCUMENT>
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    <SEQUENCE>3
    <FILENAME>d261205dex81.htm
    <DESCRIPTION>EX-8.1
    <TEXT>
    Document 3 - file: d261205dex81.htm

    </DOCUMENT>
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    <TYPE>EX-8.2
    <SEQUENCE>4
    <FILENAME>d261205dex82.htm
    <DESCRIPTION>EX-8.2
    <TEXT>
    Document 4 - file: d261205dex82.htm

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    <SEQUENCE>5
    <FILENAME>d261205dex991.htm
    <DESCRIPTION>EX-99.1
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    Document 5 - file: d261205dex991.htm

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    <SEQUENCE>6
    <FILENAME>d261205dex992.htm
    <DESCRIPTION>EX-99.2
    <TEXT>
    Document 6 - file: d261205dex992.htm

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    <TYPE>EX-99.3
    <SEQUENCE>7
    <FILENAME>d261205dex993.htm
    <DESCRIPTION>EX-99.3
    <TEXT>
    Document 7 - file: d261205dex993.htm

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    <TYPE>EX-99.4
    <SEQUENCE>8
    <FILENAME>d261205dex994.htm
    <DESCRIPTION>EX-99.4
    <TEXT>
    Document 8 - file: d261205dex994.htm

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    <DESCRIPTION>GRAPHIC
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    Document 9 - file: g261205g00m72.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 10 - file: g261205g10y10.jpg

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    Document 11 - file: g261205g12a14.jpg

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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 12 - file: g261205g12a15.jpg

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    <SEQUENCE>13
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 13 - file: g261205g15m12.jpg

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    Document 14 - file: g261205g15m13.jpg

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    Document 15 - file: g261205g25l59.jpg

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    <SEQUENCE>16
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 16 - file: g261205g78w29.jpg

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    <TEXT>
    Document 17 - file: g261205g95l58.jpg

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