Schedule 13G/A                                    Page _____ of _____ Pages
                                                          1       11







                                   UNITED STATES
                         SECURITIES AND EXCHANGE COMMISSION
                               Washington, D.C. 20549


                                    SCHEDULE 13G

                      Under the Securities Exchange Act of 1934
                                 (Amendment No. ___)*
                                                 20







                                  NUCOR CORPORATION
                 ___________________________________________________
                                  (Name of Issuer)


                                    COMMON SHARES
                 ___________________________________________________
                           (Title of Class of Securities)


                                      670346105
                 ___________________________________________________
                                   (Cusip Number)
                                     12/31/2005
                 ___________________________________________________
               (Date of Event Which Requires Filing of this Statement)



 Check the appropriate box to designate the rule pursuant to which this
 Schedule is filed:

 [X] Rule 13d-1(b)
 [ ] Rule 13d-1(c)
 [ ] Rule 13d-1(d)

 *The remainder of this cover page shall be filled out for a reporting
 person's initial filing on this form with respect to the subject class
 of securities, and for any subsequent amendment containing information
 which would alter the disclosures provided in a prior cover page.

 The information required in the remainder of this cover page shall not
 be deemed to be "filed" for the purpose of Section 18 of the Securities
 Exchange Act of 1934 ("Act") or otherwise subject to the liabilities
 of that section of the Act but shall be subject to all other provisions
 of the Act (however, see the Notes).

 Schedule 13G                                      Page _____ of _____ Pages
                                                          2       11

CUSIP No. ___670346105           ___
___________________________________________________
 1.  Name of Reporting Person and I.R.S. Identification No.:
     State Farm Mutual Automobile Insurance Company 37-0533100
______________________________________________________________________________
 2.  Check the appropriate box if a Member of a Group
     (a) _____
     (b) __X__
______________________________________________________________________________
 3.  SEC USE ONLY:
______________________________________________________________________________
 4.  Citizenship or Place of Organization: Illinois
______________________________________________________________________________
 Number of    5.  Sole Voting Power: 10,818,400
 Shares       _______________________________________________________________
 Beneficially 6.  Shared Voting Power: 0
 Owned by     _______________________________________________________________
 Each         7.  Sole Dispositive Power: 10,818,400
 Reporting    _______________________________________________________________
 Person With  8.  Shared Dispositive Power: 43,512
______________________________________________________________________________
 9.  Aggregate Amount Beneficially Owned by each Reporting Person: 10,861,912
______________________________________________________________________________
10.  Check Box if the Aggregate Amount in Row 9 excludes Certain Shares: ____
______________________________________________________________________________
11.  Percent of Class Represented by Amount in Row 9: 6.97  %
______________________________________________________________________________
12.  Type of Reporting Person: IC
______________________________________________________________________________

 Schedule 13G                                      Page _____ of _____ Pages
                                                          3       11

CUSIP No. ___670346105           ___
___________________________________________________
 1.  Name of Reporting Person and I.R.S. Identification No.:
     State Farm Life Insurance Company 37-0533090
______________________________________________________________________________
 2.  Check the appropriate box if a Member of a Group
     (a) _____
     (b) __X__
______________________________________________________________________________
 3.  SEC USE ONLY:
______________________________________________________________________________
 4.  Citizenship or Place of Organization: Illinois
______________________________________________________________________________
 Number of    5.  Sole Voting Power: 266,200
 Shares       _______________________________________________________________
 Beneficially 6.  Shared Voting Power: 0
 Owned by     _______________________________________________________________
 Each         7.  Sole Dispositive Power: 266,200
 Reporting    _______________________________________________________________
 Person With  8.  Shared Dispositive Power: 4,040
______________________________________________________________________________
 9.  Aggregate Amount Beneficially Owned by each Reporting Person: 270,240
______________________________________________________________________________
10.  Check Box if the Aggregate Amount in Row 9 excludes Certain Shares: ____
______________________________________________________________________________
11.  Percent of Class Represented by Amount in Row 9: 0.17  %
______________________________________________________________________________
12.  Type of Reporting Person: IC
______________________________________________________________________________

 Schedule 13G                                      Page _____ of _____ Pages
                                                          4       11

CUSIP No. ___670346105           ___
___________________________________________________
 1.  Name of Reporting Person and I.R.S. Identification No.:
     State Farm Fire and Casualty Company 37-0533080
______________________________________________________________________________
 2.  Check the appropriate box if a Member of a Group
     (a) _____
     (b) __X__
______________________________________________________________________________
 3.  SEC USE ONLY:
______________________________________________________________________________
 4.  Citizenship or Place of Organization: Illinois
______________________________________________________________________________
 Number of    5.  Sole Voting Power: 1,400,000
 Shares       _______________________________________________________________
 Beneficially 6.  Shared Voting Power: 0
 Owned by     _______________________________________________________________
 Each         7.  Sole Dispositive Power: 1,400,000
 Reporting    _______________________________________________________________
 Person With  8.  Shared Dispositive Power: 5,330
______________________________________________________________________________
 9.  Aggregate Amount Beneficially Owned by each Reporting Person: 1,405,330
______________________________________________________________________________
10.  Check Box if the Aggregate Amount in Row 9 excludes Certain Shares: ____
______________________________________________________________________________
11.  Percent of Class Represented by Amount in Row 9: 0.90  %
______________________________________________________________________________
12.  Type of Reporting Person: IC
______________________________________________________________________________

 Schedule 13G                                      Page _____ of _____ Pages
                                                          5       11

CUSIP No. ___670346105           ___
___________________________________________________
 1.  Name of Reporting Person and I.R.S. Identification No.:
     State Farm Investment Management Corp.
______________________________________________________________________________
 2.  Check the appropriate box if a Member of a Group
     (a) _____
     (b) __X__
______________________________________________________________________________
 3.  SEC USE ONLY:
______________________________________________________________________________
 4.  Citizenship or Place of Organization: Delaware
______________________________________________________________________________
 Number of    5.  Sole Voting Power: 484,000
 Shares       _______________________________________________________________
 Beneficially 6.  Shared Voting Power: 7,115
 Owned by     _______________________________________________________________
 Each         7.  Sole Dispositive Power: 484,000
 Reporting    _______________________________________________________________
 Person With  8.  Shared Dispositive Power: 7,115
______________________________________________________________________________
 9.  Aggregate Amount Beneficially Owned by each Reporting Person: 491,115
______________________________________________________________________________
10.  Check Box if the Aggregate Amount in Row 9 excludes Certain Shares: ____
______________________________________________________________________________
11.  Percent of Class Represented by Amount in Row 9: 0.31  %
______________________________________________________________________________
12.  Type of Reporting Person: IA
______________________________________________________________________________

 Schedule 13G                                      Page _____ of _____ Pages
                                                          6       11

CUSIP No. ___670346105           ___
___________________________________________________
 1.  Name of Reporting Person and I.R.S. Identification No.:
     State Farm Insurance Companies Employee Retirement Trust 36-6042145
______________________________________________________________________________
 2.  Check the appropriate box if a Member of a Group
     (a) _____
     (b) __X__
______________________________________________________________________________
 3.  SEC USE ONLY:
______________________________________________________________________________
 4.  Citizenship or Place of Organization: Illinois
______________________________________________________________________________
 Number of    5.  Sole Voting Power: 933,600
 Shares       _______________________________________________________________
 Beneficially 6.  Shared Voting Power: 0
 Owned by     _______________________________________________________________
 Each         7.  Sole Dispositive Power: 933,600
 Reporting    _______________________________________________________________
 Person With  8.  Shared Dispositive Power: 4,580
______________________________________________________________________________
 9.  Aggregate Amount Beneficially Owned by each Reporting Person: 938,180
______________________________________________________________________________
10.  Check Box if the Aggregate Amount in Row 9 excludes Certain Shares: ____
______________________________________________________________________________
11.  Percent of Class Represented by Amount in Row 9: 0.60  %
______________________________________________________________________________
12.  Type of Reporting Person: EP
______________________________________________________________________________

 Schedule 13G                                      Page _____ of _____ Pages
                                                          7       11

CUSIP No. ___670346105           ___
___________________________________________________
 1.  Name of Reporting Person and I.R.S. Identification No.:
     State Farm Insurance Companies Savings and Thrift Plan for U.S.
         Employees  37-6091823

______________________________________________________________________________
 2.  Check the appropriate box if a Member of a Group
     (a) _____
     (b) __X__
______________________________________________________________________________
 3.  SEC USE ONLY:
______________________________________________________________________________
 4.  Citizenship or Place of Organization: Illinois
______________________________________________________________________________
 Number of    5.  Sole Voting Power: 1,088,400
 Shares       _______________________________________________________________
 Beneficially 6.  Shared Voting Power: 0
 Owned by     _______________________________________________________________
 Each         7.  Sole Dispositive Power: 1,088,400
 Reporting    _______________________________________________________________
 Person With  8.  Shared Dispositive Power: 0
______________________________________________________________________________
 9.  Aggregate Amount Beneficially Owned by each Reporting Person: 1,088,400
______________________________________________________________________________
10.  Check Box if the Aggregate Amount in Row 9 excludes Certain Shares: ____
______________________________________________________________________________
11.  Percent of Class Represented by Amount in Row 9: 0.69  %
______________________________________________________________________________
12.  Type of Reporting Person: EP
______________________________________________________________________________

 Schedule 13G                                      Page _____ of _____ Pages
                                                          8       11



Item 1(a) and (b).  Name and Address of Issuer & Principal Executive Offices:
                    _________________________________________________________
                   NUCOR CORPORATION
                   2100 REXFORD ROAD
                   CHARLOTTE, NC  28211

Item 2(a).  Name of Person Filing: State Farm Mutual Automobile Insurance
            _____________________
                                   Company and related entities;  See Item 8
                                   and Exhibit A

Item 2(b).  Address of Principal Business Office: One State Farm Plaza
            ____________________________________
                                                  Bloomington, IL 61710

Item 2(c).  Citizenship: United States
            ___________

Item 2(d) and (e).  Title of Class of Securities and Cusip Number: See above.
                    _____________________________________________

Item 3.  This Schedule is being filed, in accordance with 240.13d-1(b).
         _____________________________________________________________
         See Exhibit A attached.

Item 4(a).  Amount Beneficially Owned: 15,055,177 shares
            _________________________

Item 4(b).  Percent of Class: 9.67 percent pursuant to Rule 13d-3(d)(1).
            ________________

Item 4(c).  Number of shares as to which such person has:
            ____________________________________________
           (i) Sole Power to vote or to direct the vote: 14,990,600
           (ii) Shared power to vote or to direct the vote: 7,115
           (iii) Sole Power to dispose or to direct disposition of:14,990,600
           (iv) Shared Power to dispose or to direct disposition of: 64,577

Item 5.  Ownership of Five Percent or less of a Class: Not Applicable.
         ____________________________________________

Item 6.  Ownership of More than Five Percent on Behalf of Another Person: N/A
         _______________________________________________________________

Item 7.  Identification and Classification of the Subsidiary Which Acquired
         __________________________________________________________________
         the Security being Reported on by the Parent Holding Company: N/A
         ______________________________________________________________

Item 8.  Identification and Classification of Members of the Group:
         _________________________________________________________
         See Exhibit A attached.

Item 9.  Notice of Dissolution of Group:  N/A
         ______________________________

 Schedule 13G                                      Page _____ of _____ Pages
                                                          9       11



  Item 10.  Certification.  By signing below I certify that, to the best of
  my knowledge and belief, the securities referred to above were
  acquired and are held in the ordinary course of business and were not
  acquired and are not held for the purpose of or with the effect of
  changing or influencing the control of the issuer of the securities and
  were not acquired and are not held in connection with or as a participant
  in any transaction having that purpose or effect.

                                      Signature

  After reasonable inquiry and to the best of my knowledge and belief,
  I certify that the information set forth in this statement is true,
  complete and correct.


      1/24/2006
  ________________________
      Date



     /s/ Paul N. Eckley
  ________________________
  Paul N. Eckley
  Senior Vice President - Investments
       State Farm Mutual Automobile Insurance Company
       State Farm Life Insurance Company
       State Farm Fire and Casualty Company



     /s/ Paul N. Eckley
  _________________________
  Paul N. Eckley
  Senior Vice President
       State Farm Investment Management Corp.
       State Farm Associates` Funds Trust
       State Farm Variable Product Trust
       State Farm Mutual Fund Trust



      /s/ Michael L. Tipsord
  _________________________
  Michael L. Tipsord
  Trustee
       State Farm Insurance Companies Employee Retirement Trust
       State Farm Insurance Companies Savings and Thrift Plan for U.S.
       Employees


 Schedule 13G                                      Page _____ of _____ Pages
                                                         10       11

                            EXHIBIT A


This Exhibit lists the entities affiliated with State Farm Mutual
Automobile Insurance Company ("Auto Company") which might be deemed to
constitute a "group" with regard to the ownership of shares reported
herein.

Auto Company, an Illinois-domiciled insurance company, is the parent
company of multiple wholly owned insurance company subsidiaries,
including State Farm Life Insurance Company, and State Farm Fire and
Casualty Company.  Auto Company is also the parent company of State
Farm Investment Management Corp. ("SFIMC"), which is a registered
transfer agent under the Securities Exchange Act of 1934 and a
registered investment advisor under the Investment Advisers Act of
1940.  SFIMC serves as transfer agent and investment adviser to State
Farm Associates' Funds Trust, State Farm Variable Product Trust, and
State Farm Mutual Fund Trust, three Delaware Business Trusts that are
registered investment companies under the Investment Company Act of
1940.  Auto Company also sponsors two qualified retirement plans for
the benefit of its employees, which plans are named the State Farm
Insurance Companies Employee Retirement Trust and the State Farm
Insurance Companies Savings and Thrift Plan for U.S. Employees
(collectively the "Qualified Plans").

As part of its corporate structure, Auto Company has established an
Investment Department.  The Investment Department is directly or
indirectly responsible for managing or overseeing the management of
the investment and reinvestment of assets owned by each person that
has joined in filing this Schedule 13G.  Moreover, the Investment
Department is responsible for voting proxies or overseeing the voting
of proxies related to issuers the shares of which are held by one or
more entities that have joined in filing this report.  Each insurance
company included in this report and SFIMC have established an
Investment Committee that oversees the activities of the Investment
Department in managing the firm's assets.  The Trustees of the
Qualified Plans perform a similar role in overseeing the investment of
each plan's assets.

Pursuant to Rule 13d-4 each person listed in the table below
expressly disclaims "beneficial ownership" as to all shares as to
which such person has no right to receive the proceeds of sale of the
security and disclaims that it is part of a "group".


 Schedule 13G                                      Page _____ of _____ Pages
                                                         11       11


                                                               Number of
                                                              Shares based
                                             Classification   on Proceeds
Name                                          Under Item 3      of Sale
____                                         ______________   ____________

State Farm Mutual Automobile Insurance Company   IC        10,861,912 shares
State Farm Life Insurance Company                IC           270,240 shares
State Farm Fire and Casualty Company             IC         1,405,330 shares
State Farm Investment Management Corp.           IA                 0 shares
State Farm Associates Funds Trust - State
    Farm Growth Fund                             IV           265,600 shares
State Farm Associates Funds Trust - State
    Farm Balanced Fund                           IV           218,400 shares
State Farm Variable Product Trust                IV             7,115 shares
State Farm Insurance Companies Employee
    Retirement Trust                             EP           938,180 shares
State Farm Insurance Companies Savings and
    Thrift Plan for U.S. Employees               EP
  Equities Account                                            872,200 shares
  Balanced Account                                            216,200 shares
State Farm Mutual Fund Trust                     IV                 0 shares
                                                    -----------------
                                                           15,055,177 shares