Executive Order on Strengthening Buy-American Preferences for Infrastructure Projects Issued on: January 31, 2019

(c) “Manufactured products” means items and construction materials composed in whole or in part of non-ferrous metals such as aluminum; plastics and polymer-based products such as polyvinyl chloride pipe; aggregates such as concrete; glass, including optical fiber; and lumber.

https://www.whitehouse.gov/presidential-actions/executive-order-strengthening-buy-american-preferences-infrastructure-projects/

This effectively means we will no longer purchase any of these materials from other countries, including Canada.