High load capacity collapsible carts

A collapsible cart configured to transition from a closed condition where it is folded up to an open condition where it is expanded for use, the collapsible cart comprising:

• a rigid frame forming a compartment, the rigid frame having a front wall, a rear wall, a right sidewall, a left sidewall, and a bottom wall, the right sidewall and the left sidewall are configured to fold inwardly in the closed condition;
• the right sidewall comprising a first right panel rotatably coupled to a second right panel;
• a first track formed along the first right panel and the second right panel extending from a first position on the first right panel to a second position on the second right panel;
• and
• a first slideable member cooperatively engaged to the first track, the first slideable member is movable along the first track between an open position to a closed position to selectively lock the first right panel to the second right panel, wherein the first slideable member is in the open position when disposed along the first track adjacent the first position of the first track while not disposed along the second right panel and is in the closed position when disposed along the first track adjacent the second position of the first track while being disposed across both the first right panel and second right panel.