LEONIA, N.J. — Monday was Day 1 of this borough’s unusual response to a deluge of traffic from navigation apps, and change was in the air.

Perhaps it was the scores of “Do Not Enter” signs newly placed at the foot of streets across the borough, with the affected hours, and a small indication that residents are exempt. Or the 3,000 yellow tags that now hang in residents’ vehicles, allowing local police to tell with a quick glance whether a vehicle is from out of town.

Or maybe it was just the handful of news helicopters that hovered above the borough at 5:45 a.m., ready to document what Leonia had wrought by instituting a near-total ban on out-of-town motorists on its streets during the morning and afternoon rush hours.

The effect on Monday was muted: The local police chief, Tom Rowe, decided to introduce the initiative with an education phase, and so officers gave only warnings to more than 150 drivers attempting to turn onto closed roads between 6 and 10 a.m.