54 U. S. COAST AND GEODETIC SURVEY 
through 1948, except for Miami, where the observations cover the 17 year period 
1932-1948. The horizontal line in each diagram represents the average sea level for 
the years used at each station. 
Figure 26 shows that with regard to detailed features, each station has a distinctive 
curve of annual variation in sea level. But in general this curve is much the same for 
relatively large stretches of the coast. Moreover, all along the Atlantic coast of the 
United States from Maine to Florida, sea level is lowest in the winter months ard highest 
in the fall months. 
The range of the annual variation increases more or less regularly from Maine to 
the mouth of Chesapeake Bay. At Eastport this range is 0.12 foot; New York, 0.58 
foot; Atlantic City, 0.54 foot; Baltimore, 0.78 foot. From Chesapeake Bay to Florida 
the pattern of variation is smn the same, but the range varies. At Norfolk it is 0.58 
foot; Charleston, 0.83 foot; Mayport, 1.03 feet; Miami Beach, 0.85 foot. 
South of Chesapeake Bay, there appears a well- disso secondary maximum 
and minimum, respectively, in May or June and in July. It is of interest to note that - 
this secondary variation appears to be present in much diminished range in the northern 
stations also. 
Gulf Coast.—In Figure 27 are shown the curves of annual variation at six stations 
on the United States coast of the Gulf of Mexico, from Key West to Port Isabel near 
the Mexican border. For Key West, Pensacola, and Galveston these curves are based 
on the 19 year period 1930-1948; for Cedar Keys on 10 years, 1939-1948 ae for Port 
Isabel on 4 years, 1944-1948. 
All along the Gulf coast, sea level is lowest in the winter months and highest in the 
fall months, the range of this variation bemg: Key West, 0.71 foot; Cedar Keys, 0.80 
foot; Pensacola, 0.76 foot, Galveston, 0.81 foot; Port Isabel, 0.86 foot. Both Galveston 
and Port Isabel show a well-developed secondary maximum in May and a secondary 
minimum in July, while the other stations indicate the presence of this secondary 
variation, but in much less marked degree. 
Pacific Coast.—For the Pacific coast of continental United States, Figure 28 gives 
the curves of annual variation at 7 stations from San Diego to Seattle. For all the 
stations with the exception of Crescent City, the curves are derived from 19 years of 
observations 1930-48. For the latter station the curve is derived for the 14-year 
period 1933-47. 
The pattern of variation is much the same from San Diego to San Francisco, a 
stretch of some 450 miles. Sea level is lowest in April and highest in September, the 
range being: San Diego, 0.50 foot; La Jolla, 0.47 foot; Los Angeles, 0.50 foot; San 
Francisco, 0.34 foot. In this connection it should be noted that the San Diego tide 
station is located within San Diego Bay, La Jolla, and Los Angeles on the open coast, 
while the San Francisco tide station is located in San Francisco Bay which receives the 
drainage waters from the Sacramento and San Joaquin Rivers. 
The Astoria tide station is located at Tongue Point, about 15 miles upstream from 
the mouth of the Columbia River. The curve of sea level variation at this station 
therefore reflects also the variation in discharge of the Columbia River. Lowest sea 
level at Astoria comes in August and highest in December, the range being 0.72 foot. 
At Seattle the pattern of variation is quite different from that at the stations on 
the California coast. Highest sea level comes in December and lowest in August as at 
Astoria, and the range is 0.52 foot. 
