Ka-Boom…!
“Gee, looks like we’re gonna need a few new wall-builder guys…”
Asteroids are like an immune system. They re nature’s way of destroying pathologically intelligent life, before intelligent life spreads to and infects other planets.
Wait – is that a jibe?
If I chose to do nothing, would I then have to delete the e-mails? 
1.8 PSI would certainly blow out windows, and probably do some serious damage to less than sturdy buildings.
And a 6000 km radius includes everything from the point where Argentina, Bolivia and Paraguay join, to nearly Anchorage, AK, and from Greenland to Hawaii. Pretty big circle you’ve drawn there.
Most of it is water, and a lot is not densely populated land, but it would seem kind of irresponsible as the POTUS to deliberately do something that would essentially be putting your own country at terrible risk, when you can absolutely prevent that. And just about any option other than having it impact in the Canadian Arctic runs the risk of landing it somewhere inhabited, or causing a huge tsunami.
So… bye bye Mexico City.
Yes, but a pinprick compaired to my original simulation. At first, I put in buddah_david’s figure of one mile (and dense rock hitting bedrock at the default 45 degree angle and at a realistic 30 kps.) With an asteroid that size, the overpressure at 100 miles is 27.7 psi (and a 106 dB sound, and a radiant flux of 132 times that of the sun.) A bit more of a problem than the 10 gigaton pebble.
The Earth’s radius is 6,371 km, so actually (now that I’m noticing) that 6,000 km radius means–given that Mexico City is north of the equator–the northern range of that uncertainty would miss the Earth entirely and fly past the north pole. Remember, from the asteroid’s point of view, the Earth is like a flat disc, not a globe that it is walking around the circumference of.