Modular transfer units for delivering items

A method comprising:

• laterally loading a first bin into a first opening of a first transfer unit at a first location,
• wherein the first bin comprises a first cavity having at least a first item therein, wherein the first transfer unit comprises a first frame and a plurality of openings in a first face of the first frame, wherein each of the plurality of openings is aligned parallel to a lateral axis of the first transfer unit, wherein the first opening is one of the plurality of openings, and wherein at least a first dimension of the first bin corresponds to at least one dimension of the first opening;
• coupling the first transfer unit to a first vehicle at the first location,
• wherein the first transfer unit is coupled to the first vehicle with a longitudinal axis of the first transfer unit aligned with respect to a forward orientation of the first vehicle, and wherein the first vehicle is configured for travel via at least a first transit mode;
• transporting, by at least the first vehicle, the first transfer unit from the first location to a second location via the first transit mode;
• and
• decoupling the first transfer unit from the first vehicle at the second location.