Previously unseen Brinkster's AS 33055 BCC-65-182-96-0-PHX took first place. AS 10439 CARINET leapt from #8 last month to #4 for March for the U.S., and was up to second place at the end of the month. Six ASNs joined the U.S. top 10: were they all due to snowshoe spam, too? Brinkster was so bad it made #8 on the world top 10!
Last month's winner AS 21788 NOC finally cleaned up its act a bit, dropping from #1 to #5. Six ASNs dropped out of the top 10. Four of them (Webhost-ASN-1, LIMESTONENETWORKS, PEER1, and ATMLINK) popped to the top 10 last month due to snowshoe spam. The other two (NTT and Charter's ASNs) didn't even have to spam less to drop out, because this month's top 10 had so much more spam.
But the US ASNs that got worse pushed the U.S. to #1 spamming country. The slope of that U.S. world top 10 curve for the last dozen days of March looks just like the Brinkster and CARINET ASN curves in the U.S. top 10. Very impressive, to drive the whole country into the countries top 10!