AUSTIN, Texas (AP) — Following the horror of a human-smuggling attempt that left 53 people dead, Republican Gov. Greg Abbott ordered state troopers to inspect more trucks — again expanding a border security mission that has cost billions, given the National Guard arrest powers and bused migrants to Washington, D.C.

What Abbott's get-tough plans haven't done in the year since he began rolling them out is curb the number of people crossing the border.

Along the border in Texas, where officials say Monday's fatal tractor-trailer journey began, U.S. authorities stopped migrants from crossing illeg...