Indeed. It's not as bad as mapping address => sales tax (no ZIP Code isn't good enough), but only because it doesn't change as often and tends to follow county boundaries when it doesn't follow state boundaries.
Another good example. Arizona doesn't follow Daylight Savings, but the Navajo Nation, which includes the Four Corners area and is in three states, does observe the change.
However the Hopi reservation, completely surrounded by Navajo territory, is entirely in Arizona, and does not observe DST. So it can get quite complicated and it's not enough to say "Arizona doesn't have Daylight Savings Time".
Another good example. Arizona doesn't follow Daylight Savings, but the Navajo Nation, which includes the Four Corners area and is in three states, does observe the change.
However the Hopi reservation, completely surrounded by Navajo territory, is entirely in Arizona, and does not observe DST. So it can get quite complicated and it's not enough to say "Arizona doesn't have Daylight Savings Time".