Extreme precipitation plays a crucial role in human society and natural systems. Observations show that extreme precipitation has been increasing over the United States in recent decades, with the largest increase over the Northeast region. Based on a recently developed high-resolution (4-km, hourly) observational database (2004 – 2017) of mesoscale convective systems (MCSs) and isolated deep convection (IDC), we investigate the climatological characteristics of four different types of precipitation (MCS, IDC, stratiform, and tropical cyclone) over the Mid-Atlantic region and their connections to precipitation in other regions in the summer. Results show that both MCS and IDC accounts for about one-quarter of the total summer precipitation amount. And, most MCSs are initiated outside the Mid-Atlantic region and propagate into the region, while most IDC events are initiated within the region. We also examine the contributions of the four precipitation types to extreme summer precipitation and find that MCS contributes more to extreme precipitation than IDC on a daily scale, while IDC contributes more to extreme precipitation than MCS at an hourly scale. The separation of different precipitation types in their contributions to extreme precipitation provides a foundation for understanding and quantifying how the contributions may change in the future.