175 miles is roughly 9% of the 1933 miles of the border between the U.S. and Mexico. The border   61f5  already has over 700 miles of fencing in place. Add in the 175 and in reality the border would be 50% fenced off. Now understand that you only need a wall between 1000 and 1200 miles to shut off more than 95% of all illegal crossings. Most of the border you have natural barriers such a mountains and deserts that are prohibitive to cross on foot.  To put it into perspective how long that additional 175 miles of fencing will be, imagine a wall being built between New York City and Baltimore Maryland.