US Chain Letters

Recently Games Magazine had a Wild Card entry where the goal was to find the longest chain of US States where the last letter of an entry in the chain had to be the same as the first letter of the next entry.
Here are three more challenging problems.
1. Find the longest chain using the two-letter US Post office codes for the 50 states.
2. Same as 1. but add the postal codes for the District of Columbia and the five US Territories for a total of 56 two-letter codes.
3. Same as 2. but add the postal codes for the three Possessions.
https://faq.usps.com/s/article/What-are-the-USPS-abbreviations-for-U-S-states-and-territories
L. Flynn