GMC Sierra Denali 2006 Owner's Manual page 248

Freeway Driving
Mile for mile, freeways — also called thruways, parkways,
expressways, turnpikes, or superhighways — are the
safest of all roads. But they have their own special rules.
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The most important advice on freeway driving is: Keep
up with traffic and keep to the right. Drive at the same
speed most of the other drivers are driving. Too-fast or
too-slow driving breaks a smooth traffic flow. Treat
the left lane on a freeway as a passing lane.
At the entrance, there is usually a ramp that leads to
the freeway. If you have a clear view of the freeway as
you drive along the entrance ramp, you should begin
to check traffic. Try to determine where you expect
to blend with the flow. Try to merge into the gap at close
to the prevailing speed. Switch on your turn signal,
check your mirrors, and glance over your shoulder as
often as necessary. Try to blend smoothly with the
traffic flow.
Once you are on the freeway, adjust your speed to the
posted limit or to the prevailing rate if it is slower.
Stay in the right lane unless you want to pass.
Before changing lanes, check your mirrors. Then use
your turn signal.
Just before you leave the lane, glance quickly over your
shoulder to make sure there is not another vehicle in
your blind spot.