Does income reported on Form 1040, Line 21 need to be entered separately on a state return? TurboTax did not automatically apply it to my state return.

Yes, as the amount from line 21 on your federal 1040 form would only apply to your federal return.  When you are getting to the "file" section for your state return, if you have a state refund on your return, you should be asked if you want any of your state refund applied to 2019 taxes.

Thank you for your reply, Julie. To clarify, I'm not asking about a refund. My question is, why doesn't TurboTax automatically transfer the income I entered on line 21 of (Form 1040) to my state return? Everything else I entered on my federal return was automatically transferred to my state return.