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   &lt;div style="font-family: 'Times New Roman',Times,serif"&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 12pt"&gt;&lt;b&gt;7. Debt&lt;/b&gt;
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;Total debt consisted of the following:
   &lt;/div&gt;
   &lt;div align="center"&gt;
   &lt;table style="font-size: 10pt; text-align: left" cellspacing="0" border="0" cellpadding="0" width="100%"&gt;
   &lt;!-- Begin Table Head --&gt;
   &lt;tr valign="bottom"&gt;
       &lt;td width="76%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="1%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="1%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="1%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="1%"&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr style="font-size: 8pt" valign="bottom"&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right" colspan="2"&gt;As of&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right" colspan="2"&gt;As of&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr style="font-size: 8pt" valign="bottom"&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right" colspan="2"&gt;June 30,&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right" colspan="2"&gt;December 31,&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr style="font-size: 8pt" valign="bottom"&gt;
       &lt;td nowrap="nowrap" align="left"&gt;&lt;i&gt;(millions)&lt;/i&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right" colspan="2"&gt;2010&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right" colspan="2"&gt;2009&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;!-- End Table Head --&gt;
   &lt;!-- Begin Table Body --&gt;
   &lt;tr style="font-size: 1px"&gt;
       &lt;td colspan="9" align="left" style="border-top: 1px solid #000000"&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom" style="background: #cceeff"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:15px; text-indent:-15px"&gt;6.3% senior notes
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="left"&gt;$&lt;/td&gt;
       &lt;td align="right"&gt;500&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="left"&gt;$&lt;/td&gt;
       &lt;td align="right"&gt;500&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:15px; text-indent:-15px"&gt;7.75% senior notes, net of discount
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;499&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;499&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom" style="background: #cceeff"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:15px; text-indent:-15px"&gt;9.75% senior notes, net of discount
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;295&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;295&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:15px; text-indent:-15px"&gt;10% convertible senior notes, net of discount
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;381&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;380&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom" style="background: #cceeff"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:15px; text-indent:-15px"&gt;Ship mortgage facility
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;46&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;49&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:15px; text-indent:-15px"&gt;Industrial revenue bonds
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;239&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;239&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr style="font-size: 1px"&gt;
       &lt;td colspan="9" align="left" style="border-top: 1px solid #000000"&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom" style="background: #cceeff"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:15px; text-indent:-15px"&gt;Total
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="left"&gt;$&lt;/td&gt;
       &lt;td align="right"&gt;1,960&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="left"&gt;$&lt;/td&gt;
       &lt;td align="right"&gt;1,962&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr style="font-size: 1px"&gt;
       &lt;td colspan="9" align="left" style="border-top: 3px double #000000"&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;!-- End Table Body --&gt;
   &lt;/table&gt;
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 12pt"&gt;CREDIT FACILITY
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;Our credit facility allows for revolving loans and letters of credit (up to $250&amp;#160;million) in
   an aggregate principal amount not to exceed the lesser of (i) $500&amp;#160;million or (ii)&amp;#160;a borrowing base
   determined by reference to the trade receivables and inventory of USG and its significant domestic
   subsidiaries. The credit facility is guaranteed by our significant domestic subsidiaries and
   secured by their and USG&amp;#8217;s trade receivables and inventory. This facility is available to fund
   working capital needs and for other general corporate purposes. Borrowings under the credit
   facility bear interest at a floating rate based on an alternate base rate or, at our option, at
   adjusted LIBOR plus 3.00%. We are also required to pay annual facility fees of 0.75% on the entire
   facility, whether drawn or undrawn, and fees on outstanding letters of credit. We have the ability
   to repay amounts outstanding under the credit agreement at any time without prepayment premium or
   penalty. The credit facility matures on August&amp;#160;2, 2012.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;The credit agreement contains a single financial covenant that would require us to maintain a
   minimum fixed charge coverage ratio of 1.1 to 1.0 if and for so long as the excess of the borrowing
   base over the outstanding borrowings under the credit agreement is less than $75&amp;#160;million. As of the
   date of this report, our fixed charge coverage ratio was 0.07 to 1. Because we do not currently
   satisfy the required fixed charge coverage ratio, we must maintain borrowing availability of at
   least $75&amp;#160;million under the credit facility. The credit agreement contains other covenants and
   events of default that are customary for similar agreements and may limit our ability to take
   various actions.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Taking into account the most recent borrowing base calculation delivered under the credit
   facility, which reflects trade receivables and inventory as of June&amp;#160;30, 2010, outstanding letters
   of credit and the $75&amp;#160;million availability requirement for the fixed charge coverage ratio not to
   apply, borrowings available under the credit facility were approximately $123&amp;#160;million. As of June
   30, 2010, there were no borrowings under the facility and outstanding letters of credit totaled $82
   million. Had there been any borrowings as of that date, the applicable interest rate would have
   been 3.53%.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 12pt"&gt;SENIOR NOTES
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;We have $300&amp;#160;million in aggregate principal amount of 9.75% senior notes due 2014 that are
   recorded on the condensed consolidated balance sheets at $295&amp;#160;million, which is net of debt
   discount of $5&amp;#160;million. Our obligations under the notes are guaranteed on a senior unsecured basis
   by certain of our domestic subsidiaries.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;We have $500&amp;#160;million of 7.75% senior notes due 2018 that are recorded on the condensed
   consolidated balance sheets at $499&amp;#160;million, which is net of debt discount of $1&amp;#160;million. The
   interest rate payable on these notes is subject to adjustment from time to time by up to 2% in the
   aggregate if the debt ratings assigned to the notes decrease or thereafter increase. At our current
   credit ratings, the interest rate on these notes is 9.5%. We also have $500&amp;#160;million of 6.3% senior
   notes due 2016.
   &lt;/div&gt;
   &lt;!-- Folio --&gt;
   &lt;!-- /Folio --&gt;
   &lt;/div&gt;
   &lt;!-- PAGEBREAK --&gt;
   &lt;div style="font-family: 'Times New Roman',Times,serif"&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;The 9.75% senior notes, 7.75% senior notes and 6.3% senior notes are senior unsecured
   obligations and rank equally with all of our other existing and future unsecured senior
   indebtedness. The indentures governing the notes contain events of default, covenants and
   restrictions that are customary for similar transactions, including a limitation on our ability and
   the ability of certain of our subsidiaries to create or incur secured indebtedness. The 9.75%
   senior notes also contain a provision requiring us to offer to purchase those notes at a premium of
   101% of their principal amount (plus accrued and unpaid interest) in the event of a change in
   control. The 7.75% senior notes and the 6.3% senior notes contain a provision requiring us to offer
   to purchase those notes at a premium of 101% of their principal amount (plus accrued and unpaid
   interest) in the event of a change in control and a related downgrade of the rating on the notes to
   below investment grade by both Moody&amp;#8217;s Investors Service and Standard &amp;#038; Poor&amp;#8217;s Financial Services
   LLC. All three series of notes also contain a provision that allows us to redeem the notes in whole
   at any time, or in part from time to time, at our option, at a redemption price equal to the
   greater of (1)&amp;#160;100% of the principal amount of the notes being redeemed and (2)&amp;#160;the sum of the
   present value of the remaining scheduled payments of principal and interest on the notes being
   redeemed discounted to the redemption date on a semi-annual basis at the applicable U.S. Treasury
   rate plus a spread (as outlined in the respective indentures), plus, in each case, any accrued and
   unpaid interest on the principal amount being redeemed to the redemption date.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 12pt"&gt;CONVERTIBLE SENIOR NOTES
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;We have $400&amp;#160;million aggregate principal amount of 10% convertible senior notes due 2018 that
   are recorded on the condensed consolidated balance sheets at $381&amp;#160;million as of June&amp;#160;30, 2010 and
   $380&amp;#160;million as of December&amp;#160;31, 2009, which are net of debt discount of $19&amp;#160;million and $20
   million, respectively, as a result of an embedded derivative. The notes bear cash interest at the
   rate of 10% per year until maturity, redemption or conversion. The notes are initially convertible
   into 87.7193 shares of our common stock per $1,000 principal amount of notes which is equivalent to
   an initial conversion price of $11.40 per share, or a total of 35.1&amp;#160;million shares. The notes
   contain anti-dilution provisions that are customary for convertible notes issued in transactions
   similar to that in which the notes were issued. The notes mature on December&amp;#160;1, 2018 and are not
   callable until December&amp;#160;1, 2013, after which we may elect to redeem all or part of the notes at
   stated redemption prices, plus accrued and unpaid interest.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;The notes are senior unsecured obligations and rank equally with all of our other existing and
   future unsecured senior indebtedness. The indenture governing the notes contains events of default,
   covenants and restrictions that are customary for similar transactions, including a limitation on
   our ability and the ability of certain of our subsidiaries to create or incur secured indebtedness.
   The notes also contain a provision requiring us to offer to purchase the notes at a premium of 105%
   of their principal amount (plus accrued and unpaid interest) in the event of a change in control or
   the termination of trading of our common stock on a national securities exchange.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 12pt"&gt;SHIP MORTGAGE FACILITY
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;Our subsidiary, Gypsum Transportation Limited, or GTL, has a secured loan facility agreement
   with DVB Bank SE, as lender, agent and security trustee. As of June&amp;#160;30, 2010, both advances
   provided for under the secured loan facility had been drawn, and the total outstanding loan balance
   under the secured loan facility was $46&amp;#160;million. Of the total amount outstanding, $7&amp;#160;million was
   classified as current portion of long-term debt on our condensed consolidated balance sheets.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;The loan balance under the secured loan facility bears interest at a floating rate based on
   LIBOR plus a margin of 1.65%. The interest rate was 2.47% as of June&amp;#160;30, 2010. Each advance is
   repayable in quarterly installments in amounts determined in accordance with the secured loan
   facility agreement, with the balance of each advance repayable eight years after the date it was
   advanced, or October&amp;#160;31, 2016 and May&amp;#160;22, 2017. The secured loan facility agreement contains
   affirmative and negative covenants affecting GTL and certain customary events of default. GTL has
   granted DVB Bank SE a security interest in the Gypsum Centennial and Gypsum Integrity ships and
   related insurance, contract, account and other rights as security for borrowings under the secured
   loan facility. USG Corporation has guaranteed the obligations of GTL under the secured loan
   facility and has agreed to maintain liquidity of at least $175&amp;#160;million.
   &lt;/div&gt;
   &lt;!-- Folio --&gt;
   &lt;!-- /Folio --&gt;
   &lt;/div&gt;
   &lt;!-- PAGEBREAK --&gt;
   &lt;div style="font-family: 'Times New Roman',Times,serif"&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 12pt"&gt;CGC CREDIT FACILITY
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;Our Canadian subsidiary, CGC Inc., or CGC, has a Can. $30&amp;#160;million credit agreement with The
   Toronto-Dominion Bank. The credit agreement allows for revolving loans and letters of credit (up to
   Can. $3&amp;#160;million in aggregate) in an aggregate principal amount not to exceed Can. $30&amp;#160;million. The
   credit agreement is available for the general corporate purposes of CGC, excluding hostile
   acquisitions. The credit agreement is secured by a general security interest in substantially all
   of CGC&amp;#8217;s assets other than intellectual property.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Revolving loans under the agreement may be made in Canadian dollars or U.S. dollars. Revolving
   loans made in Canadian dollars bear interest at a floating rate based on the prime rate plus 1.50%
   or the Bankers&amp;#8217; Acceptance Discount Rate plus 3.00%, at the option of CGC. Revolving loans made in
   U.S. dollars bear interest at a floating rate based upon a base rate plus 1.50% or the LIBOR rate
   plus 3.00%, at the option of CGC. CGC may prepay the revolving loans at its discretion without
   premium or penalty and may be required to repay revolving loans under certain circumstances. The
   credit agreement matures on June&amp;#160;1, 2012, unless terminated earlier in accordance with its terms.
   The credit agreement contains customary representations and warranties, affirmative and negative
   covenants that may limit CGC&amp;#8217;s ability to take certain actions and events of default. Borrowings
   under the credit agreement are subject to acceleration upon the occurrence of an event of default.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;As of June&amp;#160;30, 2010, there were no borrowings or letters of credit outstanding under this
   credit agreement. Had there been any borrowings as of that date, the applicable interest rate would
   have been 3.88%. The U.S. dollar equivalent of borrowings available under this agreement as of June
   30, 2010 was $28&amp;#160;million.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 12pt"&gt;OTHER INFORMATION
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;The fair value of our debt was $2.085&amp;#160;billion as of June&amp;#160;30, 2010 and $2.211&amp;#160;billion as of
   December&amp;#160;31, 2009. The fair value was based on quoted market prices of our debt or, where quoted
   market prices were not available, on quoted market prices of instruments with similar terms and
   maturities or internal valuation models.
   &lt;/div&gt;
   &lt;div align="left" style="font-size: 10pt; margin-top: 6pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;As of June&amp;#160;30, 2010, we were in compliance with the covenants contained in our credit
   facilities.
   &lt;/div&gt;
   &lt;/div&gt;
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      <ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef
 -Publisher SEC
 -Name Regulation S-X (SX)
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 -Section 02
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 129
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