The first constitution was written in 1820 in only 38 days. The Missouri Constitutional Convention (1861-63) was elected to decide on secession, and made no changes to the constitution.

When was the first missouri state constitution written? Okie... think carefully first, then make a decision:
The relevant sentence in the passage is: The first constitution was written in 1820 in only 38 days. So, the answer is 1820.