Lane splitting is currently illegal in the state of Nevada. The Motorcycle Operator Manual (PDF) published by the Nevada Department of Motor Vehicles specifically mentions lane sharing, stating:
Cars and motorcycles need a full lane to operate safely. Lane sharing is usually prohibited.
Riding between rows of stopped or moving cars in the same lane can leave you vulnerable to the unexpected. A hand could come out of a window; a door could open; a car could turn suddenly. Discourage lane sharing by others. Keep a center-portion position whenever drivers might be tempted to squeeze by you.
However, the manual also says:
Maintain an adequate space cushion – when following, being followed, lane sharing, passing and being passed.
So, lane splitting is “usually prohibited” but if you’re doing it, “maintain an adequate space cushion?” Confusing, right? The manual clears it up in the Motorcycle Traffic Laws section:
Motorcyclists may not pass or ride next to another vehicle in the same travel lane.
Motorcycles may not be driven between vehicles in adjacent lanes even if the vehicles are stopped. Police officers are an exception. (NRS Chapter 486)
NRS Chapter 486 is Nevada Revised Statutes, Chapter 486 – Motorcycles and Similar Vehicles. Section 351 states:
NRS 486.351 Unlawful passing; driving abreast.
1. A person, except a police officer in the performance of his or her duty, shall not drive a motorcycle or moped between moving or stationary vehicles occupying adjacent traffic lanes.
2. Except as provided in subsection 3, a person shall not drive a motorcycle, moped or trimobile abreast of or overtake or pass another vehicle within the same traffic lane.
3. Motorcycles and mopeds may, with the consent of the drivers, be operated no more than two abreast in a single traffic lane.
In summary: no lane splitting or lane sharing in the state of Nevada. However, you can “pair up” – riders can ride two abreast, although the “preferred formation is a staggered formation.”
Get more general information at the AMA’s page on Nevada state motorcycle laws.