Alaska
General patterns from public USGS groundwater research, not a prediction for your specific well. Depth, local bedrock, and nearby land use matter more than the state line.
USGS research maps elevated naturally occurring arsenic in private well water across parts of New England, the upper Midwest, and the Southwest, tied to local bedrock and glacial-sediment geology. Arsenic has no taste, smell, or color, so testing is the only way to know.
A test is the only way to know what's in your well. Already have results? Upload them and get every reading checked against EPA levels, free.