Article II of the U.S. Constitution describes the structures and functions of the Executive Branch of the U.S. Government (The U.S. President). This Article describes the President's chief functions and duties. It outlines the President's term limits which are terms of 4 years. In addition it establishes the President as Commander and Chief of the U.S. Military as the head of the Marines, Navy, and Army. In addition it vests the power to make treaties and to appoint judges and cabinet members with Congress' approval in the hands of the President.
"Reconstruction" is actually has a double meaning: in addition to the physical act of rebuilding areas of the South is also refers to federal government intervention in the former Confederate states in order to monitor the treatment of former slaves. This period lasted until 1877.
The trans-continental railroad was completed around this time, so not only did train travel change, but was innovated so that a train could take you anywhere across the US.
In general yes, the states honored their agreement since the Articles of Confederation demanded practically nothing from the states--meaning that it wasn't hard for the states to uphold their end of the bargain.
