Removal and arrest of illegal aliens

In 2017 256,085 illegal aliens were removed from the U.S. , and 57% were convicted criminals. Also in FY2018, Enforcement and Removal Operations (ERO) arrested 158,581 aliens, 90% of whom had criminal convictions (66%), pending criminal charges (21%), or previously issued final orders (3%). The overall arrest figure represents an 11% increase over FY2017. https://www.ice.gov/features/ERO-2018

So maybe you’re thinking, then why do we need a wall if we successfully deport or arrest that many? 

1) there are already many sections of the wall protecting major cities, but leaving huge gaps, like near Laredo, TX.  More than 300 Bangladeshi illegal migrants have been arrested by Laredo Sector Border Patrol agents in Texas this fiscal year. https://onenewsnow.com/national-security/2018/06/12/texas-border-sector-arrests-306th-bangladeshi-illegal-this-year

2) why allow them in just to be removed or arrested later at the cost of a lot of manpower,

3) if they have convictions or pending charges, why do you want them living in your sanctuary city in Hispanic neighborhoods or next door to you in Cleveland or Chicago?