Why did TIA alter billboards?
Put up November 2, 1981, on lower Front Street in Santa Cruz. Covered over November 20, after being up for 18 days.
The U.S. government continued to escalate its support for the brutal El Salvador military, and continued to hide the truth from the American people, following the same pattern as Vietnam in the 1960s.
How Was It Done?
Why did TIA alter billboards?

There were as many reasons as there were participants. Here is a sampling:

number 4
Santa Cruz Phoenix, November 5-18, 1981
Phoenix newspaper