As time passed, more states came into play and the technology became more advanced. People moved from one place to another by different means, other than walking.
Sources:
http://shelledy.mesa.k12.co.us/staff/computerlab/images/KFW_5th_Grade_Westward_Expansion.jpg
https://www.google.com/searchq=westward+expansion&biw=1920&bih=956&source=lnms&tbm=isch&sa=X&ei=M6w9VPqZNM_KoATRuo
LIBw&ved=0CAYQ_AUoAQ#facrc=_&imgdii=_&imgrc=_FdXppLKrG2UVM%253A%3B8AxHFzyWm2oR5M%3Bhttp%253A%252F%252Fwww.msad40.org%252F~library-williams%252Fimages%252FLewisClarkMap.jpg%3Bhttp%253A%252F%252Fwww.msad40.org%252F~library-williams%252FWestward.html%3B525%3B299
http://img.docstoccdn.com/thumb/orig/72925863.png
http://shelledy.mesa.k12.co.us/staff/computerlab/images/KFW_5th_Grade_Westward_Expansion.jpg
https://www.google.com/searchq=westward+expansion&biw=1920&bih=956&source=lnms&tbm=isch&sa=X&ei=M6w9VPqZNM_KoATRuo
LIBw&ved=0CAYQ_AUoAQ#facrc=_&imgdii=_&imgrc=_FdXppLKrG2UVM%253A%3B8AxHFzyWm2oR5M%3Bhttp%253A%252F%252Fwww.msad40.org%252F~library-williams%252Fimages%252FLewisClarkMap.jpg%3Bhttp%253A%252F%252Fwww.msad40.org%252F~library-williams%252FWestward.html%3B525%3B299
http://img.docstoccdn.com/thumb/orig/72925863.png