Hammer Creek[1] is a 19.2-mile-long (30.9 km)[2] tributary of Cocalico Creek in Lebanon and Lancaster Counties, Pennsylvania in the United States.

Hammer Creek is dammed to form Speedwell Forge Lake before joining the Cocalico Creek downstream by the confluence of Middle Creek near the village of Rothsville.

According to the Geographic Names Information System, Hammer Creek has also been known historically as Hammar Creek.

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