Nuevo Progresso Parking
You can either park at the two commercial lots on the US side of the border and walk across the bridge or drive across the bridge and park on the street , or in commercial lots in Nueva Progresso.
ON US Side: The parking lots are located immediately before the bridge, on each side of the road. The one we generally use is on the Left side and they charge $2.00 for parking. I assume the others do the same.
On The Mexican Side: You can often find parking on the street and enterprising Mexicans will typically "Monitor" certain parking spaces. They will help you park and watch your vehicle while you are shopping for a fee. Usually, everyone gives them $1.00 and some give them another $1.00 when they leave. I guarentee , they will not refuse the money.
There are also commercial lots on the secondary streets to the immediate East and West of the main street and the one we have used charges $2.00.