Total DHS, Texas and Federal military: about 30,000. The number of persons crossing the Mexican border between official ports of entry are under 9,000 a month, or about 300 a day. Thus 30,000 staff is deployed to lower this volume and to keep it from rising.  That is, there are 100 military/law enforcement persons per  one person per day crossing the border illegally.

U.S. Army and National Guard: About 10,000. Includes both active-duty Army and National Guard troops serving under federal orders. About 1,500 Army National Guard soldiers from more than 15 states

Texas: about 5,000 Texas Army and Air National Guard. Unknown number of state troopers.

Customs and Border Control: out of a national total of about 20,000 agents,  about 15,000 are on the Mexican border.