American highways use a PG rating system for the bitumen in the asphalt. You can read about it here: https://ftp.dot.state.tx.us/pub/txdot-info/cst/tips/faq_pg.

American highways use a PG rating system for the bitumen in the asphalt. You can read about it here: https://ftp.dot.state.tx.us/pub/txdot-info/cst/tips/faq_pg.pdf https://ftp.dot.state.tx.us/pub/txdot-info/cst/tips/faq_pg.p.... Short story is yes, places where it is expected to become very hot do use asphalt that doesn't rut under higher temperatures. The only exception I know of it Death Valley, which technically requires PG 76-10, but uses 70-10 just because California deemed it wouldn't be worth it to manufacture the extra grade just for one place that doesn't see much traffic. So I guess the highways just sometimes melt in Death Valley, too. I do recall being a kid going on road trips through these deserts and noticing some of the highways were red and seemed to be made of something different. This was before the switch to the PG rating system. My dad claimed it had something to do with not melting the tire rubber of the vehicles on those roads, but I have no clue what his source was and I can't find any information about these highways, if they even still exist.