Question

The "made in the usa" campaign was popularized by unions in an effort to influence which determinant of demand

Answer 1

I think the answer is TASTE or PREFERENCE of the consumer or buyer.

There are 5 determinants of demand. These are:
1) price
2) price of related goods
3) income of buyer
4) taste or preference of buyer
5) expectations

The "made in the USA" is a type of branding that will influence buyer's taste or preference. There are a lot of inference about when goods are tagged as "made in USA".