Last but not least, the US has NEVER gone to war much less begun hostilities for 'gain'. Any military conflict that the US has endeavored, ended with the US troops evacuating the combat area (empty handed). We do not negotiate from stolen turf and we have never had any material, concrete benefit from fighting against, with or for any other nation. This record is UNMATCHED in world history.
Ummm..you planning on giving California, Nevada, Colorado, Arizona, and New Mexico back to the Mexicans?
Also, the War of 1812 was primarily fought for the purpose of conquering Canada; reason we don't own Canada isnt' because we evacuated it, it's because our invasions of Canada failed during the war and we didn't win the war.
Last but not least, the US has NEVER gone to war much less begun hostilities for 'gain'.
We invade culturally and economically, all over the globe. Now, that's a good thing IMO, but we do invade and stay, just not in the typical way. Ask the French, who get all bent out of shape because our movies, computer stuff, fast food joints, etc. are everywhere.