That book looks interesting. Thanks for the link Inok. Obviously a number of parallels can be drawn between Lincoln and Alexander II.
The United States' purchase of Alaska during the Andrew Johnson administration (largely engineered by William Seward) is another big one.
Perhaps I should correct myself then by saying there wasn't a terrible amount of Russian-US involvement between the immediate post-civil war era and World War II. The Treaty of Portsmouth stands out as the signature event in Russian-American relations during this roughly 75-year time period in between. Even in the war effort of WWI, as I previously mentioned, the two countries were not strongly associated since the US was just beginning it's military involvement at a time when Russia was fading out.
Clearly Russia and America were linked in terms of trade, and considering the size of their respective economies and the influence they wielded in world affairs they were never off each other's radar. Comparatively speaking however it seems American and Russia had closer ties and more involvement with the countries of central and western Europe then with each other. Perfectly understandable given their geographies, the language barrier, and (during the Tsar's reign) their vast differences in political composition.