The section of SR 430 from its western terminus in Ontario at SR 309 to its split from US 42 in eastern Mansfield follows the original western end of US 30S, while the portion from US 42 to the eastern terminus at SR 603 just west of Mifflin was part of mainline US 30.
The section of SR 430 that runs from its western starting point in Ontario at SR 309 to its separation from US 42 in eastern Mansfield follows the original western end of US Route 30, whereas the portion from US 42 to the eastern endpoint at SR 603 just west of Mifflin was part of the main route of US 30.