33. Which class of tide prevails in the greatest number of important harbors on the Atlantic Coast?

Semidiurnal tides are the dominant pattern on the U.S. Atlantic Coast, characterized by two nearly equal high and low waters each lunar day. This contrasts with diurnal tides (one high, one low), mixed tides (two highs/lows with unequal heights, common on the Pacific Coast), and 'interval,' which refers to timing, not tidal type.