Geographically named because of the deep southern bend of the Willapa River, South Bend was first established as a seasonal sawmill. The South Bend Lumber Company donated half its land to the NPRR to have the railroad make South Bend the terminus of the Yakima & Pacific Coast branch line.

Now the official county seat, it is an oystering and residential community. The historic Court House was built in 1910 and has one of the largest stained glass rotundas known.

The post office was first established, as with Longbeach, just using the name as one word. The change to South Bend came much later [TBD].