NEWARK, N.J. - Americans enjoying newfound liberty are expected to travel and gather for cookouts, fireworks, concerts and beach outings over the Fourth of July weekend in numbers not seen since pre-pandemic days.Yet lingering restrictions, worker shortages and significant numbers of unvaccinated people mean some may not be as free as they would like to be.And there are fears that the mixing of large numbers of vaccinated and unvaccinated Americans at a time when the highly contagious delta variant is spreading rapidly could undo some of the progress made against the scourge.Nashville is expecting as many as 400,000 people to stream into the city for its July Fourth celebration featuring country star Brad Paisley.