What does it mean for a supreme court decision to serve as a percedent

During world war ll, the untied states was a member of the allies axis european theater pacific theater

The venn diagram below shows some services provided by state and local governments. the answer choices are (1) - creating a police force, (2) - regulating taxicabs, (3) - regulating savings banks, (4) - issuing driver licenses.

What was the overall impact of eli whitneys introduction of interchangeable parts?