Exhibit 24

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint Mario Longhi, David B. Burritt and Colleen M. Darragh or any one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/Patricia Diaz Dennis

Patricia Diaz Dennis

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint Mario Longhi, David B. Burritt and Colleen M. Darragh or any one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/Dan O. Dinges

Dan O. Dinges

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint Mario Longhi, David B. Burritt and Colleen M. Darragh or any one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/John G. Drosdick

John G. Drosdick

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint Mario Longhi, David B. Burritt and Colleen M. Darragh or any one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/John J. Engel

John J. Engel

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint Mario Longhi, David B. Burritt and Colleen M. Darragh or any one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/Murry S. Gerber

Murry S. Gerber

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint David B. Burritt and Colleen M. Darragh or either one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/Mario Longhi

Mario Longhi

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint Mario Longhi, David B. Burritt and Colleen M. Darragh or any one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/Glenda G. McNeal

Glenda G. McNeal

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint Mario Longhi, David B. Burritt and Colleen M. Darragh or any one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/Robert J. Stevens

Robert J. Stevens

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint Mario Longhi, David B. Burritt and Colleen M. Darragh or any one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/David S. Sutherland

David S. Sutherland

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

That the undersigned does hereby make, constitute and appoint Mario Longhi, David B. Burritt and Colleen M. Darragh or any one of them, my true and lawful attorneys-in-fact to sign and execute for me and on my behalf United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 to be filed with the Securities and Exchange Commission, and any and all amendments to such report to be filed with the Securities and Exchange Commission pursuant to the Securities Exchange Act of 1934, as amended, in such form as they or any one or more of them may approve, and to do any and all other acts which said attorneys-in-fact may deem necessary or desirable to enable United States Steel Corporation to comply with said Act and the rules and regulations thereunder.

IN WITNESS WHEREOF, I have hereunto set my hand this 29th day of February, 2016.

/s/Patricia A. Tracey

Patricia A. Tracey