Expandable support member for an article of footwear

A method of forming an article of footwear comprising:

• providing a support member in an unexpanded state, the unexpanded support member having a first width;
• forming a plurality of internal slits in the unexpanded support member to provide a plurality of expansion component including at least a first expansion, a second expansion component, and a third expansion component, the plurality of internal slits comprising:
• a first internal slit that extends between a first strip member and a second strip member of a first expansion component, the first strip member and the second strip member of the first expansion component being joined at a first end junction;
• a second internal slit that extends between a first strip member and a second strip member of a second expansion component, the first strip member and the second strip member of the second expansion component being joined at a second end junction;
• and
• a third internal slit that extends between a first strip member and a second strip member of a third expansion component, the first strip member and the second strip member of the third expansion component being joined at a third end junction;
• forming a plurality of external slits in the unexpanded support member, the plurality of external slits comprising a first external slit separating the first and second expansion components and a second external slit separating the second and third expansion components;
• expanding the support member from the unexpanded state to an expanded state generally along a direction of the first width to increase an area of the plurality of internal slits and an area the plurality of external slits, the expanded support member having a second width that is greater than the first width;
• incorporating the support member in an upper for the article of footwear when the support member is in the expanded state;
• and
• attaching a sole structure to a lower area of the upper.