Materials used.
Where found.
6. Transportation by water. Illustrate with sand map.
(a) Need for means of transportation: of raw material to Pittsburg; of manufactured products from Pittsburg.
(b) Rivers.
The Allegheny and Monongahela bring raw materials to Pittsburg.
The Ohio carries raw materials and manufactured products away from Pittsburg.
No tracks or roadbed to be laid for river,—river always ready; Ohio deep enough for large barges; swiftness of current due to nature of slopes.
Coal and iron carried by river as far as New Orleans.