White: Drivers can stop at a white curb long enough to pick up or drop off passengers or mail, but you can't park there long-term. Yellow: Motorists can stop at a yellow curb for the length of the time posted only to load or unload passengers or freight.

In the standard American traffic color-coding system (and many international regions), a white-painted curb signifies a Passenger Loading and Unloading Zone. This means that you are permitted to stop your vehicle only for the duration required to pick up or drop off passengers or, in some jurisdictions, to deposit or collect mail from an adjacent mailbox. Parking—defined as leaving the vehicle unattended or staying for an extended period—is strictly prohibited. These zones are commonly found in high-traffic areas like airports, train stations, theaters, and schools to prevent congestion while allowing for quick transitions. It is a "pro-tip" to always look for nearby signage, as some white curbs may have time limits (e.g., 5 minutes) or specific hours of enforcement. If you park at a white curb outside of these allowances, you risk a significant fine or having your vehicle towed, as these spots are prioritized for maintaining the "flow" of traffic rather than providing a stationary parking solution for drivers.