If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. ☐

(1) Consists of (i) 4,258,768 common shares of beneficial interest, $0.01 par value per share ("Common Shares") of National Storage Affiliates Trust (the "Issuer"), of which the Reporting Person beneficially owns (A) 4,090,261 Common Shares directly and (B) 168,507 Common Shares through Nordhagen LLLP, for which the Reporting Person is the general partner, (ii) 1,419,256 Class A common units of limited partner interest ("Class A OP Units") of NSA OP, LP (the "Partnership"), of which the Reporting Person beneficially owns (A) 848,338 Class A OP Units directly and (B) 570,918 Class A OP Units through Nordhagen LLLP, for which the Reporting Person is the general partner; and (iii) 5,090 Class A OP Units issuable upon the conversion of 5,090 long-term incentive plan units of the Partnership ("LTIP Units") that are vested or may vest within 60 days of the date hereof ("Vested LTIP Units"). In addition, the Reporting Person is voluntarily including 23,415 unvested time-based LTIP Units, 89,410 unvested performance-based LTIP Units, 395,617 class X common units of limited partnership or limited liability company interest in subsidiaries (each, a "DownREIT Partnership") of the Partnership ("Class X DownREIT Units") and 163,128 Series MI Class B common units of limited partner interest ("Class B OP Units") of the Partnership held directly by the Reporting Person which are not convertible into or exchangeable for Common Shares within 60 days of the date hereof. In addition, the Reporting Person has or shares voting and investment power directly or indirectly through his spouse or entities he controls with respect to 24,066 6.000% Series A Cumulative Redeemable Preferred Shares of Beneficial Interest, $0.01 par value ("Series A Preferred Shares").

(3)  The Reporting Person has the right to cause the Partnership to redeem all or a portion of the Class A OP Units for cash in an amount equal to the market value of an equivalent number of the Issuer's Common Shares, or at the Issuer's option, for Common Shares on a one-for-one basis, subject to certain adjustments. The unvested time-based LTIP units granted to the Reporting Person under the Issuer's 2015 Equity Incentive Plan vest in annual installments along a schedule at certain times prior to and including January 1, 2022 and the unvested performance-based LTIP units granted to the Reporting Person under the Issuer's 2015 Equity Incentive Plan vest prior to and including January 1, 2022 at the end of successive three-year performance periods upon the achievement of certain performance goals. Vested LTIP units, after achieving parity with Class A OP Units, are eligible to be converted into Class A OP Units on a one-for-one basis upon the satisfaction of conditions set forth in the Partnership's agreement of limited partnership. The Reporting Person has the right to cause each DownREIT Partnership to redeem all or a portion of the Class X DownREIT Units for cash in an amount equal to the market value of an equivalent number of the Partnership's Class A OP Units, or at the Partnership's option, for Class A OP Units on a one-for-one basis, subject to certain adjustments. Class B OP Units of the Partnership are convertible into Class A OP Units (i) at the Reporting Person's election only upon the achievement of certain performance thresholds relating to the properties to which such Class B OP Units relate (a "Voluntary Conversion") or (ii) at the election of the Issuer, upon certain retirement events and qualifying terminations (a "Non-Voluntary Conversion"). For Voluntary Conversions, Class B OP Units are convertible into Class A OP Units by dividing the average cash available for distribution ("CAD") per unit on the applicable series of Class B OP Units over the one-year period prior to conversion by 110% (the "Conversion Percentage") of the CAD per unit on the OP Units determined over the same period. For Non-Voluntary Conversions, the Conversion Percentage will be 120%, 115%, or 110% depending upon the type and timing of the Non-Voluntary Conversion.

This statement on Schedule 13D (this “Schedule 13D”) relates to the common shares of beneficial interest, par value $0.01 per share ("Common Shares") of National Storage Affiliates Trust, a Maryland real estate investment trust (the "Issuer"). The address of the principal executive offices of the Issuer is 8400 East Prentice Avenue, 9th Floor, Greenwood Village, Colorado 80111.

(a)  This Schedule 13D is filed by Arlen D. Nordhagen, who is the executive chairman of the board of trustees of the Issuer. Mr. Nordhagen is the beneficial owner of the amount of Common Shares of the Issuer as set forth in Row 11 of the cover page of this Schedule 13D. Mr. Nordhagen is referred to herein as the "Reporting Person."

On March 31, 2020, the Issuer closed its previously announced mergers of each of SecurCare Self Storage, Inc. ("SecurCare") and DLAN Corporation ("DLAN") with and into newly-formed wholly owned subsidiaries of the Issuer pursuant to an agreement and plan of merger with each of SecurCare and DLAN, among others. In connection therewith, the Issuer issued 7,658,495 Common Shares and 446,697 Common Shares to former shareholders of SecurCare and DLAN respectively. Of these, the Reporting Person, who owned approximately 53% of the outstanding shares of common stock of SecurCare, received his pro rata share in connection with the SecurCare merger equal to 4,063,571 Common Shares and the Reporting Person's spouse, who owned approximately 50% of DLAN, received her pro rata share in connection with the DLAN merger equal to 223,402 Common Shares. These securities were accordingly acquired other than by purchase.

Also on March 31, 2020, as a condition to the closing of the SecurCare merger transaction described above and in Item 5 below, the following conversions and transfers occurred: (i) immediately prior to the closing of the SecurCare merger, (a) SecurCare American Portfolio, LLC, a subsidiary of the Partnership ("SAP"), converted 20,144 Class B common units of limited liability company interest held in SAP ("Class B DownREIT Units") held by Mrs. Nordhagen into 67,644 Class X DownREIT Units at the conversion ratio for the Series SC Class B OP units previously disclosed in the Issuer's Form 8-K filed on February 24, 2020 (the "Merger 8-K"), (b) SAP converted 14,367 Class B DownREIT Units held by SecurCare into 48,244 DownREIT Class X Units and (c) NSA BV DR, LLC, a wholly owned subsidiary of the Partnership and the managing member of SAP (the "SAP Manager") transferred 143,500 Class X DownREIT Units to the Reporting Person in exchange for 143,500 Class A OP Units; and (ii) immediately after the closing of the SecurCare merger and immediately prior to closing of the DLAN merger, the SAP Manager transferred 225,000 Class X DownREIT Units to the Reporting Person in exchange for 225,000 Class A OP Units. These securities were accordingly acquired other than by purchase.

On March 30, 2020, the Reporting Person purchased 27,117 Class X DownREIT Units held in Fontana Universal Self Storage, a California Limited Partnership, Corona Universal Self Storage, a California Limited Partnership, Hesperia Universal Self Storage, a California Limited Partnership, Loma Linda Universal Self Storage, a California Limited Partnership, Universal Self Storage Hesperia LLC, Universal Self Storage Highland, a California Limited Partnership, Universal Self Storage San Bernardino LLC, and Upland Universal Self Storage, a California Limited Partnership (collectively, the "Guardian DownREITs") from SecurCare at a price per unit equal $25.06. Prior to this acquisition, the Reporting Person already beneficially owned all such units through SecurCare and had a pecuniary interest in all such units except 12,729. Accordingly, the securities were acquired other than by

In addition, 898,094 of the Class A OP Units directly or indirectly owned by the Reporting Person have been pledged as collateral to Morgan Stanley Private Bank, National Association (the "Bank") in connection with a line of credit issued by the Bank to the Reporting Person. In the event of a default under the line of credit and following a foreclosure on the Class A OP Units, the Bank may cause such Class A OP Units to be exchanged for Common Shares on a one-for-one basis and the Bank may take possession of such Common Shares and vote or dispose of such Common Shares.