[tcannizzo]

Rule 8. Section 7. THE RUNNER IS OUT.
P. When, after being declared out or after scoring, an offensive player interferes
with a defensive player's opportunity to make a play on another runner.
EFFECT: The ball is dead. The runner closest to home plate at the time of the
interference is out. All runners not out must return to the last base touched
at the time of the interference.
NOTE: A runner continuing to run and drawing a throw may be considered
a form of interference. This does not apply to a batter-runner who is entitled
to run on the dropped third strike rule.

I could swear there was a recent thread about this, but I cannot find it.
As I recall, this was the citation that allows running to 1B, but not beyond 1B.