The automated spectrophotometric total alkalinity (TA) analyzer is a fast, precise, and accurate measurements of underway total alkalinity in surface seawater, which is based on single-point titration and spectrophotometric pH detection. During leg-2 of the East Coast Ocean Acidification Cruise-2 (ECOA-2) in summer 2018, the analyzer was used to obtain a dataset of surface seawater TA in the Mid-Atlantic Bight (MAB) and the South Atlantic Bight (SAB) with high spatio-temporal resolution. The calibration against aged seawater with different TA values shows high accuracy (0.91 ± 3.60 μmol kg-1, n=32) and excellent stability over 11 days (drifted no more than 0.1%). In addition, the underway TA results agree well with the shipboard TA titration on discrete samples (0.96 ± 3.96 μmol kg-1, n=56). The results show that the distribution of surface seawater TA in summer 2018 (high to low from SAB to MAB) was similar to the pattern in summer 2007 (Gulf of Mexico and East Coast Carbon Cruise-1, GOMECC-1), summer 2012 (GOMECC-2) and summer 2015 (ECOA-1). However, the surface seawater TA in SAB in summer 2018 was about 5 - 10 μmol kg-1 higher than the value in summer 2007 and 2012. Here, we proposed that the different hydrological processes and/or other carbonate parameters changes lead to the mentioned difference. More mechanism interpretation will be carried out.