We have acted as special counsel to CSX Corporation, a Virginia corporation (the “Company”), in connection with the Registration Statement on Form S-8 (the “Registration Statement”), as filed by the Company with the Securities and Exchange Commission (the “Commission”) on the date hereof pursuant to the Securities Act of 1933, as amended (the “Securities Act”), to register 14,000,000 shares of the Company’s common stock, $1.00 par value per share (the “Shares”), issuable pursuant to the CSX 2019 Stock and Incentive Award Plan (the “Plan”), as referenced in the Registration Statement.

This opinion is being furnished in accordance with the requirements of Item 8(a) of Form S-8 and Item 601(b)(5)(i) of Regulation S-K.

For purposes of the opinion expressed below, we have relied upon, among other things, our examination of such documents and records of the Company and certificates of its officers and of public officials as we deemed necessary, including (i) the Company’s Amended and Restated Articles of Incorporation, as amended through the date hereof, (ii) the Company’s Amended and Restated Bylaws, as amended through the date hereof, (iii) the resolutions of the Company’s Board of Directors approving the Plan and authorizing the registration and issuance of the Shares in accordance with the terms of the Plan, (iv) a copy of the Plan, (v) the Registration Statement and (vi) a certificate issued by the Clerk of the State Corporation Commission of the Commonwealth of Virginia on the date hereof to the effect that the Company is existing under the laws of the Commonwealth of Virginia and in good standing (the “Good Standing Certificate”).

For purposes of the opinions expressed below, we have assumed (i) the authenticity of all documents submitted to us as originals, (ii) the conformity to the originals of all documents submitted to us as copies and the authenticity of the originals thereof, (iii) the legal capacity of natural persons and (iv) the genuineness of signatures.

ATLANTA AUSTIN BANGKOK BEIJING BOSTON BRUSSELS CHARLOTTE DALLAS DUBAI HOUSTON LONDON LOS ANGELES

MIAMI NEW YORK NORFOLK RESEARCH TRIANGLE PARK RICHMOND SAN FRANCISCO THE WOODLANDS TYSONS WASHINGTON, DC

www.HuntonAK.com

We do not purport to express an opinion on any laws other than the laws of the Commonwealth of Virginia.

Based upon the foregoing and the further qualifications stated below, we are of the opinion that:

1. Based solely on the Good Standing Certificate, the Company is a corporation validly existing and in good standing under the laws of the Commonwealth of Virginia, as of the date of the Good Standing Certificate.

2. The Shares have been duly authorized and, when and to the extent issued in accordance with the terms of the Plan, the Shares will be validly issued, fully paid and nonassessable.

We hereby consent to the filing of this opinion with the Commission as Exhibit 5.1 to the Registration Statement. In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission promulgated thereunder.

This opinion is rendered as of the date hereof, and we disclaim any obligation to advise you of facts, circumstances, events or developments that hereafter may be brought to our attention and that may alter, affect or modify the opinion expressed herein. Our opinion is expressly limited to the matters set forth above and we render no opinion, whether by implication or otherwise, as to any matters beyond the matters expressly set forth herein.