Delaware is back on the coronavirus "quarantine list" of states maintained by New Jersey, New York and Connecticut -- a list that has now grown to 34 states.

That means that anyone traveling to New Jersey, New York and Connecticut from Delaware or any of the other 33 states will need to self-quarantine for 14 days after arriving.

At one point, New Jersey and New York had the highest number of COVID cases in the country. But those states have been slowing spread of the disease while other states, particularly in the west, south and midwest, have seen explosive spread.

Now, it's simpler to say which states aren't on the tri-state area list. That's only Pennsylvania, New Jersey, New York, Connecticut, Vermont, New Hampshire, Massachusetts, Maine, Michigan, Rhode Island, South Dakota, Wyoming, Colorado, Hawaii and Oregon.

D.C. and Puerto Rico are on the quarantine list, as is Alaska.

According to the tri-state quarantine guidelines, travelers arriving from states averaging daily positive test rates of 10 percent or 10 new cases per 100,000 residents over a seven-day rolling period must self-isolate.

New York Gov. Andrew Cuomo admits the quarantine itself is imperfect. He recently implemented a new mandatory health form for travelers landing at New York's airports to try to better enforce compliance with the quarantine in the Big Apple.

Failure to submit the form, which is also required for hotspot travelers who arrive in New York by other transmit means, could result in a $2,000 fine. The governor initially said hotel clerks or business partners could alert officials about violations, and that police officers who pull over out-of-state individuals for traffic infractions could enforce quarantine rules. It's not clear how many in total have been fined.

Cuomo said out-of-state travel is one of two key risks to catching coronavirus. The other is getting complacent about social distancing and masks, he said.