Here are some of the scariest haunted houses in America:

1. Knotts Scary Farm - Buena, CA
2. The Bates Motel And Haunted Hayride - Glen Mills, PA
3. Midnight Terror Haunted House - Oak Lawn, IL
4. The Dent School House - Cincinnati, OH
5. Universal Studios Halloween Horror Nights - Los Angeles, CA and Orlando, FL
6. Creepy Hollow Haunted House - Rosharon, TX
7. Purgatory Scream Park - Kingwood, TX
8. Pennhurst Asylum - Spring City, PA
9. 13th Gate - Baton Rouge, LA
10. HellsGate - Lockport, IL

Note that some of these haunted houses may not be suitable for all ages and may require a waiver to enter. Additionally, there is a controversial haunted house called McKamey Manor in Summertown, Tennessee that is known for being extremely intense and requires a 40-page waiver to participate.