How are vendors selected?
For current materials, the Library of Congress does try to find a vendor in the country of publication. However, in some areas, we have one vendor for a region; e.g., LC Overseas Offices, Caribbean area, etc. For non-current materials, we use whichever vendor offers the material; e.g., a US vendor who offers us rare European publications.
For current materials, the Library of Congress tries to find a vendor in the country of publication. However, sometimes LC has one vendor for an entire region of the world, e.g., the Caribbean. For non-current materials, LC uses any vendor offering the material, e.g., a U.S. vendor that offers rare European publications.