Seasonal differencing is often applied when reporting, for example, monthly sales. New car sales are often reported as up or down from the same period last year. Tests for the need to seasonally difference data are seasonal unit root tests. We modify the tests of Dickey, Hasza, and Fuller (1984) to investigate results for less typical, long period cases such as 1,440 minutes per day, 52 weeks per year, 365 days per year and so forth, getting some nice properties including a surprising effect of deterministic terms in the models.