Contrails

Yesterday (Wednesday) morning I noticed that there were an unusual number of contrails in the sky that were persisting rather than dissipating. Below was the view looking to the north.

 There were others looking to the south.

All of them were stretched east-west. Normally when I notice planes high above, they are traveling north-south. I did notice some planes leaving contrails going north-south, but they did not persist as the east-west ones did. The only routes that I can think of that would fly over our area on east-west routes would be traffic on Seattle/Portland to and from the east coast.