@bob_rulz
Hi, looked at your save. I've broken down my notes and suggestions into categories. Please take this as constructive criticism and with a grain of salt.
City Placement: In general, your core cities are far too spaced out. I see distances of 6 from city to city, e.g. NY, Beantown, Chicago are too far away from Washington your capital. This means that you are not using all the land available to you, which is wasted. So try distances of 3 and 4 from one city to the next. It takes a long time to get beyond 12 citizens, so there is nothing wrong with one city overlapping tiles with another city.
City/Worker Management: You're not using governors,

Some will argue for their validity, but I won't, I need to make sure the city is working on whatever tiles I want them to work on which suit to my needs. Are you using automated workers? If not, another

You might need some more workers, even though you are industrious. However, one big problem I see is that cities are working on unimproved tiles, cities that are in your core

For example, Boston is working on 2 grasslands and 1 mountain with coal that, and those tiles have neither mine nor irrigation. You won't be maximizing your cities' potential like this. This can be corrected with more workers!
Diplomacy: From what I can guess at through F4, you still have a clean rep up to the IA

And you are doing sensible gpt deals for luxuries, considering the size of your empire. Keep working on trading, you'll need it as you advance the levels.
Military: 50 cavs, 40 rifles, and 2 cav armies, that will definitely make you the the strongest military, according to your military advisor (or strongest for a warlord game

). Listen to him for his assessment of military prowess because it is based on numbers and quality, with a more heavier emphasis on quality (i think...

)
All in all, the biggest improvement should be working on not having cities work on unimproved tiles and to place your cities closer together. Everything else suggests, at least to me, that you are ready for regent. Things you can expect in Regent is a little faster tech pace, along with a little faster AI production. At regent, all handicaps for the player are gone and you are playing the AI on par now. Have fun and good luck!