Protection of the health of the United States on our southern border seems, at first sight, a stupendous task and one beset with difficulties which are well nigh insurmountable. The boundary line, extending from the Gulf of Mexico to the Pacific Ocean, runs for the greater part of its length through an extremely wild and desert country. The Rio Grande River, a meandering stream, easily crossed, and unguarded for long distances between ports of entry, forms its eastern half. The western half, marked by monuments only, is for the most part an imaginary line running through the desert. It is also practically unguarded between ports of entry.
Situated on the American side at various cities or settlements are sixteen legalized ports of entry. Eight of these are at cities or towns of fair size; seven are at small villages or settlements and one is merely a "port of entry" on