And is there an accounting anywhere where I can find that information? I have not kept track. If I sold ethereum on coinbase and bought Steem through block trades, how can I find out what the price of steem was then? Or do I need to know that?
While I can give you an answer @melinda010100, I need to stress again the disclaimer that I make no profession to being an accountant. Nor a tax expert. The only responsibility I have and accept is for my own family.
From what you can read on this subject, you'll find current opinion is the IRS classifies every crypto exchange made as a taxable event. So, to answer your question, for my family, I am tracking every transaction I make. And calculating the P & L for each.
In your case, both Coinbase and Block Trades should have transaction history for your account. Beyond that, there are a number of places where you will find crypto price history. As this post indicates, I use CoinMarketCap.
Hope that helps!