Definitive Additional Materials


(RULE 14A-101)



Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant    x

Filed by a Party other than the Registrant    ¨

Check the appropriate box:


¨    Preliminary Proxy Statement   

¨    Confidential, for Use of the Commission 

        Only(as permitted by Rule 14a-6(e)(2))

¨    Definitive Proxy Statement   
x    Definitive Additional Materials   
¨    Soliciting Material Under Rule 14a-11(c) or Rule 14a-12

Southwest Gas Corporation


(Name of Registrant as Specified In Its Charter)



(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

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  x No fee required.


  ¨ Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.


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  ¨ Fee paid previously with preliminary materials.


  ¨ Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the form or schedule and the date of its filing.


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Southwest Gas Corporation (“Southwest” or the “Company”) analyzed the proxy voting recommendations it has received from the various proxy advisory services. Based on this analysis, the Company is making available additional information, commitments and representation that it views as providing value to shareholders in their voting decisions regarding matters to be considered at the 2009 Southwest Annual Meeting of Shareholders. The additional information, commitments and representation are as follows:


  * Southwest has reviewed the payments made to Mr. Wright’s businesses during 2008, which totaled less than $1,600.00. The amount paid by the Company is immaterial in relation to the revenues generated by Mr. Wright’s businesses and does not trigger a negative independence determination.


  * Southwest has committed that Mr. Maffie, if elected as a director for 2009, will not serve on the Audit, Compensation or Nominating and Corporate Governance committees of the Board of Directors during his term.


  * Southwest has committed to recommend to the Company’s Board of Directors that the Management Incentive Plan (the “Plan”) be amended to eliminate the change in control provision that would trigger the opportunity to vest performance awards on shareholder approval of a planned change in control and to require vesting only occur in connection with consummation of a planned change in control event. The Plan amendment has been scheduled for final action by the Board of Directors at its May 6, 2009 meeting and, based on its prior decisions, is anticipated to be adopted.