What were the major land acquisition that helped the united states expand to the pacific ocean?

The townshend duties were repealed, except for the tax on textiles, tea, or glass?

Everywhere deerskin is valuable

The following passage describes an example of __negative externality in the 1980s, manufacturing power plants in the midwest burned coal with high sulfur content, which when released as smoke, mixed with moisture in the atmosphere to create an acid that blew into canada and new england. the acid fell to the earth in the form of rain, killing fish and causing deforestation and building deterioration.