If you want to get technical Trump would not be the 19th POTUS of the Republic. Trump would be the 17th POTUS of the Republic and here is why. No constitutional Congress has existed since March 27, 1861 when (7) Southern States walked out of Congress without a quorum for adjourning and therefore ending sine die. That which is called "Congress" today assembles and acts under the authority of the President acting in capacity of being Commander and Chief of the Armed Forces, under emergency war-powers rule, i.e. no law (see 12 Stat 319, which has never been repealed and exists in Title 50 USC section 212, 213, 215, Appendex 16, 26 CFR Chapter 1 section 303. 1-6 (a), and 31 CFR Chapter 5 section 500.701 Penalties)