FreeGameEmpire is a website specializing in "abandonware".
By 2012 it had a version of Imperialism, which downloads and runs in Windows 95 mode. If you have the game in progress and switch to other windows, they too will be in Windows 95 mode, which looks different and even misses some functions, such as the "Exit" "X" in the top right corner; a nuisance but workable, though you may want to close the game every couple of days to do some ordinary things on your computer in the familiar ways.
In that version of Imperialism, you do not get anything transported from a depot that is connected to a port but not to your capital if it is on the same island. (Is that the same in other versions?)