Volcanoes are full of tricks. They can build to a major eruption in a crescendo of shudders and spatters or explode with almost no warning. They can lie in wait under a magnificent snowcap, the centerpiece of a landscape of beauty that they could obliterate tomorrow, or in 10,000 years, or never again.

And there are more of them in more parts of America than you might think.

The United States Geological Survey counts 169 potentially active volcanoes in the country — some of them straight-from-the-textbook conical mountains topped with craters, and others that hardly look the part at all. About 50 of them in six states are rated high priority or highest priority for monitoring. A few have been active in modern times; others last erupted hundreds or even thousands of years ago.

Here’s a rundown of where they are.

Hawaii

The state’s land mass owes its very existence to volcanoes: Each island is the product of at least one. The Big Island has five, including Mauna Loa, the largest active volcano anywhere on earth.

Kilauea, the one that has lately been opening new fissures, spewing lava and forcing evacuations, has been erupting in one way or another continuously since the early 1980s. Mauna Loa has erupted 33 times in the last 175 years, and Loihi, a submarine volcano about 20 miles offshore, erupted in 1996. Farther north and west, the islands are older and quieter geologically; Maui’s only active volcano, Haleakala, is believed to have erupted most recently at least 400 years ago.