Final answer:
One pre-1920s limitation on political speech that is still considered precedent is prior restraint, which refers to the government's ability to prevent someone from speaking before it happens.
Step-by-step explanation:
One pre-1920s limitation on political speech that is still considered precedent is the concept of prior restraint. Prior restraint refers to the government's ability to prevent someone from speaking or expressing themselves before it happens.
The Supreme Court has ruled that prior restraint can only be imposed in the most extreme circumstances, as it is considered censorship.