The USA is generally safe for tourists, but safety varies significantly by location and context. Gun violence is a real concern in certain urban neighborhoods — research specific areas of cities you plan to visit. Downtown tourist zones in most cities are safe; avoid unfamiliar residential areas at night, especially in Baltimore, Detroit, Memphis, and parts of Chicago.
Natural hazards vary by region: hurricanes in the Southeast and Gulf Coast (June–November), tornadoes in the Midwest (spring), wildfires in the West (summer–autumn), and blizzards in the Northeast and Midwest (winter). Medical care is world-class but very expensive — comprehensive travel insurance with medical coverage is essential.