Exhibit 3.46

Prepare, sign, with an original signature and filing fee.

This is the minimum information required.

(This space for use by the Secretary of State only)

STATE OF MONTANA

ARTICLES of AMENDMENT for

PROFIT CORPORATION (35-1-230 MCA)

MAIL: BOB BROWN Secretary of State P.O. Box 202801

Helena, MT 59620-2801

PHONE: FAX: WEB SITE: (406)444-3665 (406)444-3976 sos.state.mt.us

PRIORITY

STATE OF MONTANA

FILED

JUN 03 2014

SECRETARY OF STATE

Filing Fee: $15.00

Priority Filing add $20.00

1. The current name of this Corporation is: Northwestern Resources Co.

2. The following amendment was adopted in the manner provided for by the Montana Business

Corporation Act:

Amendment changing name of corporation to “Texas Westmoreland Co.”

(Please attach additional sheets of paper if more room is needed.)

3. The date this amendment was adopted is: April 14, 2004

(Mo/day/year)

4. Please check the appropriate box and provide additional information where requested. (only check one box):

¨This amendment was adopted by a sufficient vote of the Board of Directors. A vote of the shareholders was

not required

xThis amendment was adopted by a sufficient vote of the shareholders.

There were: 10,000 shares outstanding: 10,000 voted for the

(outstanding #)

(for #)

amendment: 0 voted against.

(agains #)

NOTE: For voting groups, see help sheet on the reverse side.

Ray D. Gardner

Signature of Officer or Chair of the Board

General Counsel & Secretary June 1, 2004

Title Date

NOTE: There are important legal and accounting procedures and implications with respect to this corporate action. Suitable legal and accounting advice should be secured before submission. The Secretary of State’s office encourages that such advice be sought prior to filling out forms and to be sure that you understand the terms and procedures