PRESS: Mr. President, can you impose an export duty on anything?
PRESIDENT: I think there is a Constitutional prohibition against export duties. That is my recollection, that the Constitution says that no export duties shall be imposed. I wouldn't want to be too certain about that offhand, but that is my recollection.
* * * * * * *
Another inquiry about what the Cabinet did in relation to the farm situation. Secretary Wallace has made a careful study, especially of the wheat conditions, and the Cabinet took up and discussed several suggestions for assistance in that direction. One of them was a lowering of freight rates, especially on exports of wheat and exports of flour.
PRESS: Mr. President, has this report been made public?
PRESIDENT: I don't suppose it will be made public in its entirety, but I think you can get from Secretary Wallace an outline of some of the things he found. A proposal of that kind is already before the Interstate Commerce Commission to see what they can do. If rates are lowered for the transportation of wheat or flour, those roads in the United States that are not securing any more than is necessary for them to have to live on, will, of course, expect an increase of rates in some other direction. If all the roads of the United States were exactly alike, that, perhaps, might be easy to suggest. The main difficulty about that is that some of the roads make their living almost entirely from the transportation of agricultural products. They don't transport much of anything else and it would be very difficult to find anything that would compensate them for their loss of revenue, if there is a lowering of freight on agricultural products. But that is before the Interstate Commerce Commission and will be worked out, if possible.
Another suggestion of the possible change of the tariff on wheat. It is evident that the present tariff is working to the advantage of the American farmer on wheat. I think the spread between the price in America and the price in Canada is, or a few days ago was, something like 28 cents. That varies from one time to another. I don't know whether the suggestion of increasing the tariff would be a remedy. Of course we have a surplus of wheat here that we want to export and, where wheat is to be exported, the first thought would be to increase the tariff on it which wouldn't be of very much assistance. But that has been suggested to me by men who know something about how those things work. It is something that ought to be investigated and studied, and in their opinion it might be helpful. And for that reason that will be done. I don't want to put it out as a proposal on my part, or as something that certainly would be helpful, but, at least, it is worth considering.
Source: "The Talkative President: The Off-the-Record Press Conferences of Calvin Coolidge". eds. Howard H. Quint & Robert H. Ferrell. The University Massachusetts Press. 1964.
Calvin Coolidge, Excerpts of the President's News Conference Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/349002