Which volcanoes in the contiguous United States have erupted since the Nation was founded?

Excluding steam eruptions, these volcanoes have shown activity:

• Mount St. Helens, Washington - Eruptions and/or lava dome growth occurred in the late 1700s, 1800-1857, 1980-1986, and 2004-2008.
• Lassen Peak, California - A series of steam blasts began on May 30, 1914. An eruption occurred 12 months later on May 21, 1915. Minor activity continued through the middle of 1917.
• Mount Hood, Oregon - After being dormant for over 1,000 years, Mount Hood had an eruptive period beginning in 1781 that lasted for about a decade. In the mid-1800s, local residents reported minor explosive activity.