It is common for organizations including businesses and government offices to close down for holidays. The Review Journal listed several of the Las Vegas organizations that will be closed down this year. Some include banks, state offices, post offices, the school district, some utility companies, etc. Some are closed on both Thursday and Friday.
There will be a lot of traffic to the McCarran Airport so they are recommending 2 hour predeparture arrival at checkin.
Be safe and enjoy family and friends during the holiday.