<PAGE>

                                                                     Exhibit 2.1

                          AGREEMENT AND PLAN OF MERGER

      AGREEMENT AND PLAN OF MERGER ("AGREEMENT") entered into this 20th day of
January, 2006 between American Railcar Industries, Inc., a Missouri corporation
("PARENT"), and American Railcar Industries, Inc., a Delaware corporation
("SUBSIDIARY" and together with Parent, "CONSTITUENT CORPORATIONS").

                                    RECITALS:

      WHEREAS, the authorized capital stock of Parent consists of: (i) 12,000
shares of Common Stock, $.01 par value per share ("PARENT COMMON STOCK"), 1,195
shares of which are issued and outstanding as of the date hereof; (ii) 99,000
shares of Preferred Stock, par value $.01 per share ("PARENT OLD PREFERRED
STOCK"), one share of which is issued and outstanding as of the date hereof;
(iii) 150,000 shares of Payment-In-Kind Preferred Stock, par value $.01 per
share, none of which are issued and outstanding as of the date hereof; and (iv)
500,000 shares of New Preferred Stock, $.01 par value per share ("PARENT NEW
PREFERRED STOCK"), 82,055 shares of which are issued and outstanding on the date
hereof.

      WHEREAS, the authorized capital stock of Subsidiary consists of: (i)
50,000,000 shares of Common Stock, $.01 par value per share ("SUBSIDIARY COMMON
STOCK"), 100 shares of which are issued and outstanding and held by Parent as of
the date hereof; and (ii) 1,000,000 shares of Preferred Stock, $.01 par value
per share, none of which are issued and outstanding on the date hereof
("SUBSIDIARY PREFERRED STOCK").

      WHEREAS, the parties deem it advisable and in the best interests of the
Constituent Corporations and their stockholders that Parent be merged with and
into Subsidiary (the "MERGER") in accordance with the provisions of the Missouri
General and Business Corporation Law ("MGBCL") and the Delaware General
Corporation Law ("DGCL") and desire to state herein the mode of carrying the
same into effect and certain other details and provisions of the Merger;

      NOW, THEREFORE, in consideration of the premises and the agreements herein
contained, the parties agree as follows:

      1. Constituent Corporations and Merger. On the Effective Time, as defined
in Section 3 below, Parent shall be merged with and into Subsidiary and
Subsidiary shall be the surviving corporation (the "SURVIVING CORPORATION").

      2. Surviving Corporation.

            (a) The name by which the Surviving Corporation shall be known is:
American Railcar Industries, Inc.

            (b) The corporate purposes of the Surviving Corporation shall be the
purposes set forth in the Certificate of Incorporation of Subsidiary.

                                      -1-

<PAGE>

                                                                     Exhibit 2.1

            (c) The Certificate of Incorporation of the Surviving Corporation
shall be the Certificate of Incorporation, as supplemented by the Certificate of
Designations adopted by the Board of Directors of the Subsidiary and attached
hereto as Exhibit A (the "SURVIVING CORPORATION CERTIFICATE OF DESIGNATIONS").

            (d) The By-Laws of the Surviving Corporation shall be the By-Laws of
the Subsidiary;

            (e) The officers and directors of the Surviving Corporation shall be
those of the Subsidiary immediately prior to the Effective Time.

      3. Effective Time. Simultaneously with or immediately prior to the closing
of an initial public offering of shares of Subsidiary Common Stock pursuant to
an effective registration statement filed with the Securities and Exchange
Commission under the Securities Act of 1933, as amended, or such earlier time as
the Boards of Directors of the Parent and Subsidiary shall approve, (i) a
Certificate of Ownership and Merger and/or an executed counterpart of this
Agreement, together with the Surviving Corporation Certificate of Designations,
shall be filed with the Secretary of State of the State of Delaware pursuant to
the applicable provisions of the DGCL; and (ii) Articles of Merger shall be
filed with the Secretary of State of the State of Missouri pursuant to the
applicable provisions of the MGBCL. The Merger shall become effective when the
Certificate of Ownership and Merger and/or an executed counterpart of this
Agreement and the Articles of Merger are filed in the Offices of the Secretary
of State of the State of Delaware and the Secretary of State of the State of
Missouri, respectively (the "EFFECTIVE TIME").

      4. Effect of Merger. From and after the Effective Time, the effect of the
Merger shall be as provided in Sections 351.447, 351.450 and 351.458 of the
MGBCL and Sections 253 and 259 of the DGCL, including the following: (i) the
separate corporate existence of Parent shall cease and all of its assets,
property, rights and powers as well as all debts due it and all choses in action
belonging to it shall be transferred to and vested in the Subsidiary as the
Surviving Corporation without further act or deed; (ii) the Subsidiary as the
Surviving Corporation shall continue in existence and retain all of its assets,
property, leasehold interests, rights and powers as well as all debts due to it
and all choses in action belonging to it without impairment; and further, the
title to any real estate, or any interest therein, under the laws of the State
of Missouri vested in the Subsidiary Corporation shall not revert or be in any
way impaired by reason of the Merger; and further, the rights of creditors of
Parent, lessors of property leased by Parent and parties contracting with Parent
shall not in any manner be impaired by the Merger, and Subsidiary as the
Surviving Corporation shall remain liable for all of its liabilities and
obligations existing prior to the Effective Time and shall be deemed to have
assumed the obligations of Parent existing prior to the Effective Time to the
same extent as if Subsidiary had itself incurred such obligations; and further
the aggregate amount of the net assets of the parties which was available for
the payment of dividends immediately prior to the Merger shall continue to be
available for the payment of dividends by the Surviving Corporation.

      5. Further Assurance. If at any time Parent shall consider or be advised
that any acknowledgments or further assurances or assignments in law or other
similar actions are

                                      -2-

<PAGE>

                                                                     Exhibit 2.1

necessary or desirable to acknowledge, confirm, vest or perfect in and to the
Surviving Corporation any rights, title or interests of Parent, or otherwise to
carry out the provisions hereof, Parent and its respective officers and
directors shall and will execute and deliver any and all such acknowledgements,
assurances or assignments in law, and do all things necessary or proper to
acknowledge, confirm, vest or perfect such rights, title or interests in the
Surviving Corporation, and to otherwise carry out the provisions of this
Agreement.

      6. Statutory Agent. From and after the Effective Time, until thereafter
changed as permitted by law, the Secretary of State of the State of Missouri
shall serve as the statutory agent of the Surviving Corporation upon whom any
process, notice or demand against either Parent or the Surviving Corporation may
be served for any prior obligations for so long as any liability remains
outstanding against Parent or the Surviving Corporation in the State of
Missouri.

      7. Conversion of Shares.

            (a) At the Effective Time, by virtue of the Merger and without any
action on the part of the holder thereof, (i) each share of Parent Common Stock
issued and outstanding shall be converted into and be deemed to become 9,328.083
shares of Subsidiary Common Stock, provided that any fractional shares to be
issued to each Stockholder of the Corporation pursuant to such conversion shall
be rounded to the nearest whole number of shares and (ii) each share of Parent
New Preferred Stock issued and outstanding shall be converted into and be deemed
to become one share of Subsidiary New Preferred Stock (as defined in the
Surviving Corporation Certificate of Designations). At such time prior to the
Effective Time as shall be determined by the Board of Directors of Parent, each
share of Parent Old Preferred Stock issued and outstanding shall be redeemed
pursuant to the terms thereof and the Articles of Incorporation of the Parent.

            (b) From and after the Effective Time, (i) each certificate
theretofore representing shares of issued and outstanding Parent Common Stock
shall, upon surrender to Subsidiary, entitle the holder to receive in exchange
therefor a certificate or certificates representing the number of shares of
Subsidiary Common Stock into which the stock theretofore represented by the
certificate so surrendered shall have been converted in accordance with the
paragraph above, and (ii) each certificate theretofore representing shares of
issued and outstanding Parent New Preferred Stock shall, upon surrender to
Subsidiary, entitle the holder to receive in exchange therefor a certificate or
certificates representing the number of shares of Subsidiary New Preferred Stock
into which the stock theretofore represented by the certificate so surrendered
shall have been converted in accordance with the paragraph above.

            (c) Each share, if any, of capital stock held in Parent's treasury
at the Effective Time shall automatically be canceled.

            (d) At the Effective Time, and pursuant to Section 351.447 of the
MGBCL and Section 253 of the DGCL, all of the presently issued and outstanding
shares of Subsidiary Common Stock shall cease to exist as the Parent Corporation
holds 100% of such shares.

                                      -3-

<PAGE>

                                                                     Exhibit 2.1

      8. Dissenter's Rights. Any holder of record of shares of Parent's capital
stock who shall, at or before the taking of the vote of Parent stockholders to
adopt this Agreement and the Merger contemplated hereby, have filed with
Subsidiary written objection thereto and not have voted for the Merger and who
shall have, after the taking of such vote, properly demanded payment for such
shares in accordance with Section 351.875 of the MGBCL, shall not thereafter
have any rights as a stockholder except as provided in Section 351.900 et seq.
of the MGBCL.

      9. Abandonment. This Agreement may be terminated and the Merger abandoned
by the mutual consent of the Boards of Directors of Parent and Subsidiary at any
time prior to the filing date with the Delaware Secretary of State and the
Missouri Secretary of State, whether or not at the time of such termination and
abandonment this Agreement has been adopted by the stockholders of Parent.

      IN WITNESS WHEREOF, the parties hereto have caused their duly authorized
officers to execute this Agreement of Merger effective as of the date first
above written.

                                              AMERICAN RAILCAR INDUSTRIES, INC.,
                                              a Missouri Corporation

                                              By: /s/ James J. Unger
                                                  ------------------------------
                                              James J. Unger, President and
                                              Chief Executive Officer

ATTEST:

/s/ Michael Obertop
--------------------------------
Secretary

                                              AMERICAN RAILCAR INDUSTRIES, INC.,
                                              a Delaware Corporation

                                              By: /s/ James J. Unger
                                                  ------------------------------
                                              James J. Unger, President and
                                              Chief Executive Officer

ATTEST:

/s/ Michael Obertop
--------------------------------
Secretary

                                      -4-

<PAGE>

                                                                     Exhibit 2.1

                                    EXHIBIT A
                           CERTIFICATE OF DESIGNATIONS

                                       of

                               NEW PREFERRED STOCK

                                       of

                        AMERICAN RAILCAR INDUSTRIES, INC.

                         (Pursuant to Section 151 of the
                        Delaware General Corporation Law)

                      -------------------------------------

      American Railcar Industries, Inc., a corporation organized and existing
under the General Corporation Law of the State of Delaware (hereinafter called
the "Corporation"), hereby certifies that the following resolution was adopted
by the Board of Directors of the Corporation as required by Section 151 of the
General Corporation Law at a meeting duly called and held on January 20, 2006:

      RESOLVED, that pursuant to the authority granted to and vested in the
Board of Directors of this Corporation (hereinafter called the "Board of
Directors" or the "Board") in accordance with the provisions of the Certificate
of Incorporation of the Corporation, the Board of Directors, to be effective as
of the effective time of the merger of American Railcar Industries, Inc., a
Missouri Corporation (the "Missouri Predecessor Corporation"), with and into the
Corporation (the "Merger"), hereby designates 82,055 shares of the Corporation's
Preferred Stock, par value $.01 per share, as "New Preferred Stock" of the
Corporation and hereby states the designation and number of shares, and fixes
the relative rights, preferences, and limitations thereof as follows:

                              NEW PREFERRED STOCK:

1. Designation and Number of Shares. There shall be established a Series of the
New Preferred Stock designated as "New Preferred Stock" (such Series being
hereinafter referred to as the "New Preferred Stock"). Of the 1,000,000 shares
of Preferred Stock authorized under the Certificate of Incorporation, 82,055 are
hereby designated as New Preferred Stock, $,.01 par value.

2. Dividends.

      a. The Preferred Stock, which hereby is designated as New Preferred Stock,
is to be issued pursuant to the Merger for issued and outstanding shares of new
preferred stock, $.01 par value, of the Missouri Predecessor Corporation (the
"Predecessor Corporation New Preferred Stock"), at the effective time of the
Merger, whereby each share of Predecessor Corporation New Preferred Stock issued
and outstanding at the time of the Merger is to be converted into one share of
New Preferred Stock of this Corporation. For all purposes of this Certificate of
Designation, each share of New Preferred Stock of this Corporation issued in
connection with the Merger shall be deemed to have been issued as of the date of
issuance of the share of Predecessor Corporation New Preferred Stock for which
it was converted in the Merger, and all dividends paid or accrued by the
Predecessor Corporation in respect of each share of Predecessor Corporation New
Preferred Stock shall be deemed to have been paid or accrued in respect of the
share of New Preferred Stock for which it was converted. By way of further
clarification, the rights of each share of New Preferred Stock, with respect to
dividends (including the accumulation thereof) and liquidation preference, shall
be the same as the Predecessor Corporation New Preferred Stock for which the New
Preferred Stock was converted in the Merger.

                                      -5-

<PAGE>

                                                                     Exhibit 2.1

      b. The holders of the shares of New Preferred Stock shall be entitled to
receive, when and as declared by the Board of Directors out of funds legally
available therefore, cumulative dividends at the annual rate of 9.25% per annum
(the "NP Dividend Rate") which shall accrue daily and shall be computed on the
basis of a 365 day year or a 366 day year, as applicable, on the NP Base Amount
(which, except as provided in paragraph 2(e) below, shall initially be and shall
never be less than $1,000 per share, the "NP Base Amount") and no more (except
as specifically provided below), in annual payments on each July 1 (each of such
dates being a "NP Dividend Payment Date"), commencing with the first NP Dividend
Payment Date following the date of issuance (the "Issuance Date") of shares of
New Preferred Stock, payable as set forth hereinafter. If the NP Dividend
Payment Date is not a Business Day (as defined herein), then such dividend shall
be payable on the next succeeding Business Day. The dividend payable on the
first NP Dividend Payment Date following an Issuance Date with respect to any
issued and outstanding share of New Preferred Stock shall be the pro rata amount
of the NP Dividend Rate based upon the number of days in the period from an
Issuance Date to the first NP Dividend Payment Date following such Issuance Date
(the "Dividend Period"). Dividends on the New Preferred Stock shall be paid to
the holders of record at the close of business on the date specified by the
Board of Directors of the Corporation at the time such dividend is declared;
provided, that such date shall not be more than 60 days nor less than 10 days
prior to the respective NP Dividend Payment Date. Dividends shall be fully
cumulative and shall accrue (whether or not declared and whether or not funds
are legally available for the payment of dividends) from the first day of the
Dividend Period as to which such dividend may be payable as herein provided.
Accrued dividends which are not paid on an NP Dividend Payment Date shall be
added to the NP Base Amount on that NP Dividend Payment Date. The NP Base Amount
shall be reduced (but not below $1,000 per share) by the amount of cumulated
dividends when such accumulated dividends shall have been paid.

      Business Day shall mean each day which is neither a Saturday, Sunday nor
another day on which banking institutions in New York, New York or St. Louis,
Missouri are legally authorized or required to close.

      c. Dividends on the New Preferred Stock shall be payable solely in cash.

      d. All dividends paid with respect to shares of New Preferred Stock
pursuant to paragraphs (2)(a), 2(b) and (2)(c) shall be paid pro rata and in
like manner to all holders entitled thereto.

      e. Unless full, cumulated dividends have been or contemporaneously are
declared and paid on the New Preferred Stock through the most recent NP Dividend
Payment Date, the Corporation shall not declare or pay on any shares of the
Corporation's Common Stock any dividend, whether in cash, property or otherwise
(other than solely in additional Common Stock), nor shall the Corporation make
any distribution on any Common Stock or any warrants, rights or options
exercisable for any Common Stock or set aside any assets for such purpose (other
than solely in additional Common Stock), nor shall the Corporation purchase,
redeem or otherwise acquire any Common Stock or any warrants, rights or options
exercisable for any Common Stock (other than in exchange for additional Common
Stock).

      f. Subject to the foregoing provisions of this paragraph 2, the Board of
Directors may declare and the Corporation may pay or set apart for payment
dividends and other distributions on any Common Stock or any warrants, rights or
options exercisable for any Common Stock, and may purchase, redeem or otherwise
acquire any Common Stock or any warrants, rights or options exercisable for any
Common Stock and set aside assets for such purpose, and the holders of the
shares of the New Preferred Stock shall not be entitled to share therein.

3. Liquidation Preference.

      a. In the event of any voluntary or involuntary liquidation, dissolution
or winding up of the affairs of the Corporation, the holders of shares of New
Preferred Stock then outstanding shall be entitled to be paid out of the assets
of the Corporation available for distribution to its stockholders an amount in
cash equal to the NP Base Amount for each share of New Preferred Stock
outstanding plus an amount in cash equal to all accrued but unpaid dividends
thereon to the date fixed for liquidation (to the extent that such accrued but
unpaid dividends are not included in the NP Base Amount), before any payment
shall be made or any assets distributed to the holders of any of the Common
Stock, and no more. Upon any liquidation, dissolution or winding up of the
Corporation, the New

                                      -6-

<PAGE>

                                                                     Exhibit 2.1

Preferred Stockholders will be entitled to be paid after payment or provision of
payment to the holders of any security having a preference over the New
Preferred Stock with respect to liquidation preference. If the assets of the
Corporation are not sufficient to pay in full the liquidation payments payable
to the holders of outstanding shares of the New Preferred Stock, then the
holders of all such shares shall share ratably in such distribution of assets in
accordance with the amount which would be payable on such distribution if the
amounts to which the holders of outstanding shares of New Preferred Stock are
entitled were paid in full.

      b. For the purposes of this paragraph 3, neither the voluntary sale,
conveyance, exchange or transfer (for cash, shares of stock, securities or other
consideration) of all or substantially all or part of the property or assets of
the Corporation nor the consolidation or merger of the Corporation with one or
more other corporations shall be deemed to be a liquidation, dissolution or
winding up, voluntary or involuntary, of the affairs of the Corporation.

4. Voting Rights.

      a. In addition to the voting rights required by the General Corporation
Law of the State of Delaware, each holder of New Preferred Stock shall be
entitled to vote on all matters submitted to the holders of shares of Common
Stock.

            i. Whenever the holders of shares of New Preferred Stock are
            entitled to vote on matters submitted to the holders of shares of
            Common Stock, all such shares shall be voted together with the
            Common Stock as a single class, and shall be entitled to the number
            of votes per share of New Preferred Stock derived from the following
            formula (rounded to the nearest 100th decimal point), where "x" is
            the number of votes per share of New Preferred Stock, "p" is the
            number of issued and outstanding shares of New Preferred Stock as of
            the related record date and "c" is the number of issued and
            outstanding shares of Common Stock as of the related record date:

                                   X = 2 (c+p)
                                       -------
                                          P

            ii. In any vote by the holders of the New Preferred Stock acting as
            a separate class, every holder of New Preferred Stock shall be
            entitled to one (1) vote for each share of New Preferred Stock held
            by such holder.

      b. So long as any shares of New Preferred Stock remain outstanding, the
Corporation shall not, either directly or indirectly or through merger or
consolidation with any other corporation, without the affirmative vote, or the
written consent pursuant to Section 228 of the Delaware General Corporation Law
(or any successor provision), of the holders of a majority of the outstanding
shares of New Preferred Stock, voting separately as a class, (1) increase the
authorized number of shares of New Preferred Stock or reclassify the shares of
New Preferred Stock; (2) amend any provision of the Certificate of Incorporation
or this Certificate or any other certificate that would affect adversely the
preferences, rights or powers of the New Preferred Stock; (3) create, authorize
or issue any securities ranking on a parity with, or senior to the New Preferred
Stock with respect to the right to receive dividends and/or participate in any
other distribution of assets; (4) reclassify any shares of Common Stock into
securities ranking on a parity with, or senior to, the New Preferred Stock with
respect to the right to receive dividends and/or participate in any distribution
of assets other than by way of dividend (including any securities convertible
into or exchangeable for options, warrants or other rights to acquire such
parity or senior securities, respectively); or (5) issue any shares of preferred
stock.

5. Redemption. Notwithstanding anything in this Certificate of Designations or
the Certificate of Incorporation of the Corporation to the contrary, and without
further action by the Board of Directors or otherwise, when and if shares of New
Preferred Stock are redeemed, any outstanding shares of New Preferred Stock
shall cease to be designated as New Preferred Stock and such shares shall
automatically become authorized, unissued, and undesignated shares of Preferred
Stock.

                            [signature page follows]

                                      -7-

<PAGE>

                                                                     Exhibit 2.1

      IN WITNESS WHEREOF, this Certificate of Designations is executed on behalf
of the Corporation by its authorized officer this 20th day of January 2006.

                                               AMERICAN RAILCAR INDUSTRIES, INC.

                                               By: /s/ James J. Unger
                                                   -----------------------------
                                                   James J. Unger, President and
                                                   Chief Executive Officer

                                      -8-