If the U.S.A. ever go to war with Russia, who would win?

Russia doesn't want to invade the USA but the USA is very aggressive when it comes to war. So, in your scenario, it would be the USA trying to do the invading. If that's the case then one on one the USA would fail at invading Russia. Russia is too large, and Russia has better ground military than the USA. The USA would have to rely on it's airforce and navy to have a shot.

Russia. Americans are all too fat or have 'bone spurs'. 

We don't have to go into a conflict to win.

the Cockroaches Both the USA and Russia would glow in the Dark for 1000 years Thank God

If it is just the USA you would have to consider the history.    Russia has never been successfully invaded.   The USA on the other hand was successfully invaded and our capital city was burned.    The USA also has not done well in wars since WW II.   Korea was a draw,   Vietnam was a political loss.   etc.   The USA also subscribes to the Geneva  Conventions whereas the Russians only pay lip service to it.   Also you have to consider where the war will be fought.   I doubt the USA would try to invade Russia and Russia would not invade the USA.   So it would be a naval war or a missile war.   Nukes would be used so I doubt either would "win."   What they would do is so damage the other than China would probably take over the eastern half of Russia and the USA would never be a major player in the world again.  

Nobody wins in a Nuclear War.  We all die.

Russia is now just a shadow of the former USSR, they no longer have the equipment to invade anybody they can't reach by land.

It would depend on the type of war being waged.  If you look at the spread and acceptance of mis and disinformation as a form of warfare then Russia would win as too many Americans are ready and willing to believe conspiracy theories.

 With biological warfare both countries are fairly evenly matched. 

If nuclear weapons are used there would be no winners, just losers. 

In traditional land warfare all you have to do is look at  maps that show vegetation, soils, temperatures, etc.  If an invasion of Russia was launched from a country like Germany then it's a long way to Moscow.  You would have to consider supply line lines for troops, the time of year, the type of land.  (See what happened to Hitler's troops).  Most of Siberia is forested and uninhabited.  Some of the land is quite boggy which is a perfect habitat for insects like sand flies, black flies, horse flies. As an example. In 2019 Canada had two teenagers who were wanted for murder and fled to northern Manitoba. While the communities in the area were concerned the people also said that if the police didn't catch these killers the bugs would eat them alive. 

You also have to look at the military tactics.  The US tends to place more reliance on technology such as drone strikes while the Russians have no hesitation in placing troops on the ground. 

Then you have to look at history.  Russia has been invaded many times whereas the US, excluding the War of 1812, has not  had those experiences. How successful was the US in Viet Nam, Afghanistan? 

It also gets down to the morale of the population and how willing they are to fight a war  and accept losses of lives. 

No one would win. The only way that NATO allies would back the USA is if Russia attacked the USA. The USA would get no support from Europe to attack Russia, because Europe doesn't want another world war starting in Europe. Beside that, both countries could nuke each other into kingdom come.

Neither . That's probably why neither has started one; at least, up to now. All you need is some psychopath in charge, though. I guess