Jet Plane Smoke Lines in the Sky

The coolest thing I ever seen or heard was during the air space shut down for one week after 9/11. Was 2--3 days in to it and yep nothing in the sky all day long. One mid afternoon I heard this weird sound while outside and here comes 2 air force jets hauling ***, they went form one end of the sky to the other in a few seconds.

Maybe they were not as high up, 35,000 feet the passenger jets fly at. I think the passanger jets go 500 mph, don't know how fast those fighter jets can go but it seemed like they were going 20,000 mph, lol