Access Rules for Americans
Americans can visit Monaco without a visa for stays up to 90 days within any 180-day period—the same as Schengen rules, since access is through France.
There is no passport control between France and Monaco. You simply drive or walk across the border. This means:
Since you must pass through France to reach Monaco, the Schengen 90/180 rule applies:
On any given day, count the days you've spent in the Schengen Area over the past 180 days. You cannot exceed 90 days in any 180-day rolling window.
Monaco has no airport. Options:
Monaco-Monte Carlo station is on the main coastal line. Direct TGV connections from Paris (~6 hours).
A8 motorway from Nice (~20 minutes) or the scenic coastal roads. Note: Parking in Monaco is extremely limited and expensive.
Port Hercule accommodates mega-yachts. Many residents arrive by yacht, especially during events.
The European Travel Information and Authorisation System (ETIAS) will require Americans to obtain pre-travel authorization:
ETIAS is not a visa—just pre-authorization. The 90/180 rules remain unchanged.