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<!--Generated by DFIN XBRL Instance Document - http://www.dfinsolutions.com/ - Version R3.0 - on 21-March-2024 [07:49:54] {AM}-->
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_pkg_CapPensionServiceCostMember" xml:lang="en-US">CAP Pension Service Cost [Member]</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_pkg_FairValueAsOfYearEndOfEquityAwardsGrantedDuringTheYearMember" xml:lang="en-US">Fair Value as of Year End of Equity Awards Granted During the Year [Member]</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_pkg_PriorYearendFairValueOfAwardsThatVestedDuringTheYearMember" xml:lang="en-US">Prior YearEnd Fair Value of Awards that Vested During the Year [Member]</label>
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<loc xlink:type="locator" xlink:href="pkg-20231231.xsd#pkg_SctChangeInPensionValueMember" xlink:label="loc_pkg_SctChangeInPensionValueMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_pkg_SctChangeInPensionValueMember" xml:lang="en-US">SCT Change in Pension Value [Member]</label>
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<loc xlink:type="locator" xlink:href="pkg-20231231.xsd#pkg_SctEquityValueMember" xlink:label="loc_pkg_SctEquityValueMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_pkg_SctEquityValueMember" xml:lang="en-US">SCT Equity Value [Member]</label>
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<loc xlink:type="locator" xlink:href="pkg-20231231.xsd#pkg_YearoverYearIncreaseDecreaseInFairValueOfUnvestedAwardsGrantedInPriorYearsMember" xlink:label="loc_pkg_YearoverYearIncreaseDecreaseInFairValueOfUnvestedAwardsGrantedInPriorYearsMember" />
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