"States are prohibited (absent express congressional authorization) by the Constitution and specifically the "Foreign Commerce Clause" (I think that is Scalia's term) from adopting ANY policy - including sending bills - that hinder the federal government's foreign policy. In "the unique context of foreign commerce," a State's power is further constrained because of "the special need for federal uniformity." Wardair Canada, Inc. v. Florida Dept. of Revenue, 477 U.S. 1, 8 (1986). "In international relations and with respect to foreign intercourse and trade, the people of the United States act through a single government with unified and adequate national power.'" Japan Line, Ltd. v. County of Los Angeles<.i<, 441 U.S. 434, 448 (1979), quoting Board of Trustees v. United States, 289 U.S. 48, 59 (1933)."
The states, counties, cities and colonias along the Mexican border are all having relations, intercourse and trade with the foreign country of Mexico.