wrote in message
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I dont know what the altitude difference would be, nor how to determine
the altitude of my home, his home, and the river. But I do know there
are a lot of hills and valleys and some are quite steep!

Actually, how does someone find out the altitude of their home (or any
other place)? Is this something that can be found on the web, based on
the physical address?


Most of the country has been mapped out as to the altitude. I can get on
the county tax map and get contour lines and satalite pix of the house I
live in.

See if your county web page has a GIS map program .

Some, maybe all or most all of the GPS units will have a screen where the
altitude can be read. It does not seem to be near as accurate as the
horizontal position.

Years ago I ordered from the government some maps that had the contour lines
on it. The local library may have some, or a small local airport may be
able to help with the maps.