Is it true that in the United States all interstate highways that run east to west are even numbered and ones running north to south are odd?

Interstate numbering works like this: Odd-numbered interstates north-to-south, with the numbers increasing from west to east. (That's why I-5 is on the West Coast and I-95 is on the East Coast.) Even-numbered interstates east-to-west, with the numbers increasing from south to north. (That's why I-10 runs along the Gulf of Mexico and I-80 runs across the upper tier of the country.)

As a rule, like-numbered interstates don't cross each other (ie, an odd-numbered freeway won't cross another odd-numbered freeway). One notable exception, though, is I-85, which not only crosses I-77 north of downtown Charlotte, but also multiplexes (or runs concurrently with) I-75 through downtown Atlanta AND terminates at I-65 (at Montgomery) and I-95 (at Petersburg).

Routes with odd numbers run north-south.
Routes with even numbers run east-west.
For north-south routes, the lowest numbers are in the west.
For east-west routes, the lowest numbers are in the south.

https://www.fhwa.dot.gov/programadmin/interstate.cfm