To the Senate of the United States:
I herewith transmit, in compliance with the request of the Senate in their resolution of the 17th of June, 1846, a report of the Secretary of State, together with a copy of all "the dispatches and instructions" "relative to the Oregon treaty" "forwarded to our minister, Mr. McLane," "not heretofore communicated to the Senate," including a statement of the propositions for the adjustment of the Oregon question previously made and rejected by the respective Governments. This statement was furnished to Mr. McLane before his departure from the country, and is dated on the 12th July, 1845, the day on which the note was addressed by the Secretary of State to Mr. Pakenham offering to settle the controversy by the forty-ninth parallel of latitude, which was rejected by that minister on the 29th July following.
The Senate will perceive that extracts from but two of Mr. McLane's "dispatches and communications to this Government" are transmitted, and these only because they were necessary to explain the answers given to them by the Secretary of State.
These dispatches are both numerous and voluminous, and, from their confidential character, their publication, it is believed, would be highly prejudicial to the public interests.
Public considerations alone have induced me to withhold the dispatches of Mr. McLane addressed to the Secretary of State. I concur with the Secretary of State in the views presented in his report herewith transmitted, against the publication of these dispatches.
Mr. McLane has performed his whole duty to his country, and I am not only willing, but anxious, that every Senator who may desire it shall have an opportunity of perusing these dispatches at the Department of State.
The Secretary of State has been instructed to afford every facility for this purpose.
JAMES K. POLK.
James K. Polk, Special Message Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/201074