This paper presents the results of an analytical study on the seismic response of Multi-Span-Simply-Supported (MSSS) bridges in New Jersey. The investigation includes the detailed nonlinear dynamic analysis of three actual bridges as representatives of typical 2, 3, and 4 span bridges which are common in New Jersey and the East Coast in general. Both 2-D and 3-D models were employed in the analyses. Several parameters prove to have an important effect on the seismic response of MSSS bridges, such as soil-structure interaction, impact between adjacent spans, steel bearings, and plasticity at pier columns. The seismic response of MSSS bridges is evaluated in the light of a comprehensive parametric study based on these factors and quantified through capacity/demand (C/D) ratios for critical elements. Furthermore, the research needs related to the seismic evaluation and design of MSSS bridges are also discussed.