He based his arguments on the solid premise that the work of the topogs was vital to the country's military security and of great benefit to its economic progress.
In a further move, Secretary Poinsett ordered--on 1 August 1838--the assignment to the topogs of "all new works of improvement, not of a military character, [and] not connected with the fortifications.
During the late 1830s and 1840s, a number of topogs conducted widespread explorations of the West.
In 1846-48, many of the topogs were withdrawn from civil projects to participate in the war with Mexico.
The acquisition of the vast Southwest from Mexico, as a result of the war, and the settlement of the Oregon controversy with Britain, opened up the Far West for further exploration by the topogs and the undertaking of numerous boundary surveys.