From Alaska:

"If your trip includes more than one flight on Alaska Airlines and/or one of our airline partners, we will check your bags to the final destination on your ticket as long as there are fewer than 12 hours between flights.

If you will be in the connecting city for 12 hours or longer, you will need to claim and re-check your baggage. Additional baggage fees may apply."

Source: https://www.alaskaair.com/content/tr...e/checked-bags