1871 - The Civil War has taught the nation that if it wishes to hold the Pacific Coast firmly to the Union, efficient transport will have to be provided, to limit the chance that some foreign country might annex California. Due to concerns of the Indian Reserves, construction is slow up to 1881, but then the Atlantic Pacific Railroad is rushed to completion with princely subsidies of land and money.
1930 - To counter the Great Depression, the U.S. Government finances Hoover Dam Project. Las Vegas receives thousands of depression-weary job seekers, who help build the world's largest gravity dam.
1970 - Tourism comes of age as major economic activity, in Las Vegas and in beautiful Arizona.
Version 2.4 (March 2013):
* Update for Mac users. Version 2.4 file posted at end of this thread.
Version 2.3 (October 2012):
* Expensive tunnels fixed. Version 2.3 file posted at end of this thread.

Version 2.2 (April 2007):
* Mail Cars fixed. Thanks to Slappy Da Clown for nailing this problem.
Version 2.1 (Improvements mainly by Universum):
* More realistic mountains around Flagstaff, better vegetation generally.
* Phoenix added as starting location for Robber Barons, Barstow is winable by Investors.
* Overpass bridges enabled.
* Events file localized, events improved.
* Universum has provided two small batch files: one to enable expensive tunnels, and one to disable them, so that Arizona Gold and all other scenarios have regular tunnels. Simply copy the unzipped AZCanyonV2 folder into your UserMaps directory. Run the appropriate batch file in the AZCanyonV2 folder by double-clicking on it.
Version 1
*16x16 map. Topography derived from digital elevation model (DEM) data.
* Realistically priced tunnels and bridges.
With thanks to all the dedicated people providing insight and new ideas in the wiki and forum. Special credits to Universum (scenario ideas), Dr Frag (large maps), gforce (realistic tunnel and bridge prices), Stormfather (redefined industries).