Southwest Border Port-of-Entry Infrastructure Improvement Act

Southwest Border Port-of-Entry Infrastructure Improvement Act - Directs the Commissioner of Customs to update the Ports of Entry Infrastructure Assessment Study and develop priorities for port-of-entry infrastructure improvement projects in the United States (which may include port-to-Federal-highway connections) along the Southwest border.

Establishes in the Department of Transportation the Southwest Border Infrastructure Fund. Authorizes the Secretary of Transportation to make grants from the Fund to an eligible applicant through the North American Development Bank to pay the U.S. contribution of costs for projects to develop the physical port-of-entry infrastructure along the Southwest border in order to reduce the negative environmental impact, particularly with respect to air, soil, and water quality, associated with cross-border transportation.

Directs the Secretary of the Treasury to establish a site to carry out a port-of-entry technology demonstration program to test and evaluate new port-of-entry technologies, refine them as well as operational concepts, and train personnel under realistic conditions.