desire to maintain friendly relations with the Mexican Republic and to cause its rights and territories to be respected, not only by our citizens, but by foreigners who have resorted to the United States for the purpose of organizing hostile expeditions against some of the States of that Republic.  The defenseless condition in which its frontiers have been left has stimulated lawless adventurers to embark in these enterprises and greatly increased the difficulty of enforcing our obligations of neutrality.  Regarding it as my solemn duty to fulfill efficiently these obligations not only toward Mexico, but other foreign nations, I have exerted all the powers with which I am invested to defeat such proceedings and bring to punishment those who by taking a part therein violated our laws.  The energy and activity of our civil and military authorities have frustrated the designs of those who meditated expeditions of this character except in two instances.  One of these, composed of foreigners, was at first countenanced and aided by the Mexican Government itself, it having been deceived as to their real object.  The other, small in number, eluded the vigilance of the magistrates at San Francisco and succeeded in reaching the Mexican territories; but the effective measures taken by this Government compelled the abandonment of the undertaking.

The commission to establish the new line between the United States and Mexico, according to the provisions of the treaty of the 30th of December last, has been organized, and the work is already commenced.

Our treaties with the Argentine Confederation and with the Republics of Uruguay and Paraguay secure to us the free navigation of the river La Plata and some of its larger tributaries, but the same success has not attended our endeavors to open the Amazon.  The reasons in favor of the free use of that river I had occasion to present fully in a former message, and, considering the cordial relations which have long existed between this Government and Brazil, it may be expected that pending negotiations will eventually reach a favorable result.

Convenient means of transit between the several parts of a country are not only desirable for the objects of commercial and personal communication, but essential to its existence under one government.  Separated, as are the Atlantic and Pacific coasts of the United States, by the whole breadth of the continent, still the inhabitants of each are closely bound together by community of origin and institutions and by strong attachment to the Union.  Hence the constant and increasing intercourse and vast interchange of commercial productions between these remote divisions of the Republic.  At the present time the most practicable and only, commodious routes for communication between them are by the way of the isthmus of Central America.  It is the duty of the Government to secure these avenues against all danger of interruption.