Excess time delays of transionospheric radio signals introduce ranging errors in satellite-navigation and radar systems, which are directly proportional to the total electron content (TEC) along the propagation path. Correlation between TEC at Fort Monmouth, NJ (40.18degN,74.06degW) and Richmond, FL (25.60degN,80.40degW) was determined. The correlation analysis was performed at monthly and daily intervals for the equinoctial and winter periods during the quiet phase of the solar cycle. Positive maxima of monthly correlation coefficients weregsim 0.9for data comparisons at identical or nearly identical times, and decreased when the data sets were shifted in time with respect to each other. Positive maxima of daily correlation coefficients were, in general,gsim 0.9. Seasonal variations were noticeable.