HEARTLAND EXPRESS INC

901 Heartland Way

North Liberty, Iowa 52317

PROXY STATEMENT

FOR ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD MAY 9, 2024

GENERAL INFORMATION

This Proxy Statement (the "Proxy Statement") is furnished in connection with the solicitation of proxies from the stockholders of Heartland Express to be voted at the Annual Meeting, which will be held at our headquarters, 901 Heartland Way, North Liberty, Iowa 52317, Thursday, May 9, 2024, at 8:00 a.m. Central Daylight Time, and any adjournment thereof. THE ENCLOSED PROXY IS SOLICITED BY OUR BOARD OF DIRECTORS. All costs of the solicitation will be borne by the Company. The approximate date of mailing this Proxy Statement and the enclosed form of proxy is March 29, 2024.

We are using the SEC's Notice and Access model ("Notice and Access") that allows us to deliver proxy materials via the Internet. We believe Notice and Access provides stockholders with a convenient method to access the proxy materials and vote, while allowing us to conserve natural resources and reduce the costs of printing and distributing the proxy materials. A Notice of Availability of Proxy Materials (the "Notice") was first mailed on or about March 29, 2024, to stockholders of record at the close of business on March 11, 2024 (the "Record Date"). The Internet Notice will instruct you as to how you may access and review the proxy materials. The Proxy Statement, the proxy card, and our Annual Report for the year ended December 31, 2023 ("Annual Report") are first being made available to stockholders on or about March 29, 2024.

How to Read this Proxy Statement

This Proxy Statement contains the proposals to be considered by stockholders at the Annual Meeting, as well as important information concerning, among other things: our management and our Board of Directors; executive compensation; transactions between us and our officers, directors, and affiliates; the stock ownership of management and other large stockholders; the services provided to us by and fees of our independent registered public accounting firm; and instructions for stockholders who want to make proposals at the 2025 Annual Meeting. Each stockholder should read this information before completing and returning the enclosed proxy card.

PROXY STATEMENT

Why am I receiving this proxy statement?

Our Board of Directors (the "Board") has made available to you the Notice of Annual Meeting, this Proxy Statement, our Annual Report, proxy card, and voter instruction card (collectively, "Proxy Solicitation Materials") either on the Internet or by mail in connection with the Annual Meeting. The Company will bear all costs associated with this proxy solicitation. You are receiving this Proxy Statement because you owned shares of Heartland Express common stock at the close of business on the Record Date, and that entitles you to vote at the Annual Meeting. By use of a proxy, you can vote whether or not you participate in the Annual Meeting. This Proxy Statement describes the matters on which we would like you to vote and provides information on those matters so that you can make an informed decision.

What is Notice and Access and why did Heartland Express elect to use it?

We make the Proxy Solicitation Materials available to stockholders electronically via the Internet under the Notice and Access regulations of the SEC.

Most of our stockholders have received the Notice in lieu of receiving a full set of Proxy Solicitation Materials in the mail. The Notice includes information on how to access and review the Proxy Solicitation Materials, and how to vote, via the Internet. We believe this method of delivery will decrease costs, expedite distribution of Proxy Solicitation Materials to you, and reduce our environmental impact.

Stockholders who received the Notice but would like to receive a printed copy of the Proxy Solicitation Materials in the mail should follow the instructions in the Notice for requesting such materials.

What will I be voting on?

•Election of directors

•Ratification of the independent registered public accounting firm for 2024

•An advisory, non-binding vote, on executive compensation

How do I vote?

You can vote either at the Annual Meeting orby proxy. We urge you to vote by proxy even if you plan to participate in the Annual Meeting so that we will know as soon as possible that enough votes will be present for us to hold the meeting. If you participate in the meeting, you may vote at the meeting and your prior proxy will not be counted.

To vote your shares, follow the instructions in the Notice, voting instruction form, or the enclosed proxy card. Telephone and Internet voting is available to all registered and most beneficial holders.

Stockholders voting by proxy may use one of the following three options:

•fill out the enclosed voter instruction form or proxy card, sign it, and mail it in the enclosed postage-paid envelope;

•vote by Internet(if available, instructions are on the voter instruction form, proxy card, or Notice); or

•vote bytelephone prior to the Annual Meeting(if available, instructions are on the voter instruction form, proxy card, or Notice).

If you hold your shares in "street name," please refer to the information forwarded by your bank, broker, or other holder of record to see the options available to you.

The telephone and Internet voting facilities for stockholders to vote prior to the Annual Meeting will close at 11:59 p.m. Eastern Daylight Time on May 8, 2024. If you vote by telephone or over the Internet prior to the Annual Meeting, you may incur costs, such as telephone and Internet access charges, for which you will be responsible. The telephone and Internet voting procedures are designed to authenticate stockholders and to allow you to confirm that your instructions have been properly recorded.

Can I change my proxy vote?

Yes. Any stockholder giving a proxy vote has the power to revoke it at any time before it is exercised by:

•revoking it by written notice to Mr. Joshua S. Helmich, our Secretary, at the address on the cover of this Proxy Statement;

•delivering a later-dated proxy (including a telephone or Internet vote); or

•voting in person at the meeting.

If you hold your shares in "street name," please refer to the information forwarded by your bank, broker, or other holder of record for procedures on revoking or changing your proxy.

How many votes do I have?

You will have one vote for each share of Heartland Express common stock that you owned at the close of business on March 11, 2024.

How many shares are entitled to vote?

There were 79,034,376 shares of Heartland Express common stock outstanding and 27,768 shares granted, but not vested, under the Heartland Express, Inc. 2011 Restricted Stock Award Plan and 2021 Restricted Stock Award Plan as of the Record Date that are entitled to vote at the meeting. Each share is entitled to one vote. We have no other class of stock outstanding. There is no cumulative voting.

How many votes must be present to hold the meeting?

In order to transact business at the Annual Meeting, a quorum must be present. A quorum is present if forty percent (40%) of the issued and outstanding shares of Common Stock as of the Record Date are represented at the Annual Meeting in person or by proxy. Shares that are entitled to vote but that are not voted at the direction of the holder (called "abstentions") and shares that are not voted by a broker or other record holder due to the absence of instructions from the beneficial owner (called "broker non-votes") will be counted for the purpose of determining whether a quorum is present.

How many votes are needed for the proposals to pass and how are votes tabulated?

The election of directors (Proposal 1) requires an affirmative vote of a plurality of the votes cast, which means that with respect to Proposal 1, the seven director nominees receiving the highest number of votes for their election will be elected. The ratification of our independent registered public accounting firm for 2024 (Proposal 2), and the vote on executive compensation (Proposal 3), will require the affirmative vote of a majority of the votes cast at the meeting. For purposes of determining the number of votes cast with respect to a particular matter, only those cast "For" or "Against" are included. If no direction is specified by the stockholder, the proxy will be voted "For" Proposals 1, 2 and 3, and at the discretion of the proxy holders, upon such other matters as may properly come before the meeting or any adjournment thereof. Proxies marked "Abstain" and broker non-votes are counted only for purposes of determining whether a quorum is present at the meeting. With respect to the vote on executive compensation (Proposal 3) this vote is non-binding on the Board. Although non-binding, the Board will review and consider the voting results when evaluating our executive compensation program.

A vote to "abstain" on the election of directors will haveno effect on the outcome. A vote to "abstain" on the other proposals will also haveno effect on the outcome.

If you vote "abstain," your shares will be counted as present for purposes of determining whether enough votes are present to hold the Annual Meeting.

Votes cast at the Annual Meeting will be tabulated by the Inspector of Elections and the results of all items voted upon will be announced at the Annual Meeting.

What if I don't return my proxy card and don't participate in the Annual Meeting?

If you are a holder of record (that is, your shares are registered in your own name with our transfer agent) and you do not vote your shares, your shares will not be voted.

If you hold your shares in "street name," and you do not give your bank, broker, or other holder of record specific voting instructions for your shares, your record holder can vote your shares on the ratification of the independent registered public accounting firm. However, your record holder cannot vote your shares without your specific instructions on the election of directors and the advisory approval of executive compensation.

For the proposals on which a broker cannot vote without your instruction, if you do not provide voting instructions to your broker, the votes will be considered "broker non-votes" and will not be counted in determining the outcome of the vote. "Broker non-votes" will be counted as present for purposes of determining whether enough votes are present to hold the Annual Meeting.

What happens if a nominee for director declines or is unable to accept election?

If you vote by proxy, and if unforeseen circumstances make it necessary for the Board to substitute another person for a nominee, we will vote your shares for that other person.