I rode about 300 miles through Three Rivers and Seven Lakes, without
getting a drop on me.  And when I reined in, I looked up to see the
state flag fluttering in the breeze.  Who is the person and what state
did he end up in?

This might help:

New Mexico
"Leaving Three Rivers, travel east on US Hwy. 54, west on US Hwy 380,
north on Interstate 25, west on NM Hwy 6, west on Interstate 40, north
on NM Hwy 371, and east on NM Hwy 57 puts you in Seven Lakes - exactly
300.8 miles."

http://www.funtrivia.com/ubbthreads/showflat.php?Cat=0&Number=369892&an=0&page=0

Rainbow~

outwit2,

I believe this has already been asked:

this link contains a discussion and (most likely) the correct answer.

http://answers.google.com/answers/threadview?id=424667

outwit2,

I apologize, your question is slightly different.  Although the ink I
gave you mentions the state it does not address who the rider is.  I
hope you still find it helpful, though.