It was unfortunate that Chinese scientists "proved" last month that time travel is physically impossible--since it ruins my goal of going back to key points in history to warn those involved of the long-term effects of their decisions. I wouldn't try to "change" history--but rather just "tweak" it so things turn out a little better down the line.
The first stop would be the Constitutional Convention of 1787. I would like to be on hand to offer a few suggestions for items that our Founding Fathers might want to include in the document that would guide the operation of our nation. I'd start with adding something to that First Amendment to make it clear if contributing to a political candidate represents "freedom of speech". Of course, after explaining what our current election process is like, Messers Jefferson, Madison and Monroe might reconsider that whole "we don't need a King" thing.
This might also be a good time to ask if carrying a gun on you is what they mean by "bear and keep arms" in the Second Amendment. Since this was a time that an angry bear or Indian might step out of the woods at any time--I'm guessing they would say "yes". I'll suggest they put something in there about abortion as well. That might settle a few arguments 175-years later.
My next stop in the time machine is 1913 as voters and Congress consider the 16th Amendment--establishing the Federal Income Tax. I would let them know that less than 100-years later, only about half of Americans will be paying any income tax--with some even getting a net gain from the process. I'd suggest that they consider a "consumer based" form of taxation--as that would increase the amount of revenue and make sure that everyone pays "their fair share". I'd bring the 17-thousand page Tax Code with me as well--but that might put the time machine over its weight limit.
Up next is a short hop to 1935 as Congress votes to establish the Social Security program. Here I would warn the lawmakers that in just 70-years, it won't be that uncommon for a person to live into their 90's--meaning they would be drawing on the system for more than 25-years. They should also know that the 20-workers-to-1-retiree ratio seen at their time will edge closer to just 2-to-1 in the next millineum. I'd leave themn with a suggestion to consider tying the eligibility age to the life-expentency of the average American--keeping most people in the program for the ten years they anticiapted back then.
The Wayback Machine makes another short hop to 1965 as again we need to warn Congress about the impact of the Medicare program. I'd better come armed with information on the number of people who will be enrolled in the program just 45 years later--and a price sheet showing the prohibitively high costs of some life-saving procedures that will become common place in the future. Hopefully some of the other suggestions I have made in the past will have been adopted--so that revenue streams are bigger and eligibilities for entitlement programs are tighter. I guess a screen capture on the 14-trillion dollar debt ceiling crisis might be just as effectivve as well.
Alas, my dream of going back to "fix" some of our modern-day problems before they start will remain just that--a dream. Hopefully those that continue to live in an economic fantasyland won't make it any more of a nightmare going forward.