US-States, again

This is a variation of List of US-states without common letters . This is supposed to be more difficult and challenging than the original problem.

Create a list of US-States, one name per line, such that no two consecutive States in the list do contain any common letter (and such that each State occurs at most once).

This is an example:

Texas
Wyoming
Utah
New York

You have 2 tasks:

1. Determine the maximum number $N$ of States in such a list.
2. Determine the maximum number $L$ of letters in such a list (that is, the sum of the lengths of all the States' names in the list).

The second task is probably more difficult than the first one. I will accept only answers with a complete solution. If nobody comes up with a solution within 72 hours, I will add a hint.

Assuming a state can't appear twice in the list (if it could, then the answer to both questions is infinite):

The maximum length of the list is 21, and the maximum of L is 151, or 149 if you don't count spaces in two-word states.

Counting or not counting spaces does not affect the resulting list of states, which is:

1. Florida,
2. Kentucky
3. Idaho
4. New Jersey
5. Oklahoma
6. Tennessee
8. Mississippi
9. New York
10. Alabama
11. Connecticut
13. Vermont
14. Hawaii
15. Oregon
16. Utah
17. Wyoming
18. Texas
19. Ohio