There was great unification among a majority of americans around the democratic-republicans and the nation was prospering economically. thus, the period is often referred to as the era of good feelings

You seem to be giving a statement more than asking a question, but the period you describe ran from about 1815 to 1825, and is most closely associated with the presidency of James Monroe.

The phrase "Era of Good Feelings" was coined by a journalist, Benjamin Russell, in the Boston newspaper, Columbian Centinel, on July 12, 1817.  Russell used that term to describe the new era taking shape, especially as Monroe's presidency began, after Monroe visited Boston as part of a goodwill tour of the US.  President Monroe certainly went along with the description and was trying to evoke that "good feelings" sort of mood in the country.  Historians see "The Era of Good Feelilngs" as having begun around 1815, after the War of 1812 and the end of Napoleon's wars in Europe, when the United States entered an era when it could focus on its own affairs and not need to be concerned about political and military happenings in Europe.  The "Era of Good Feelings" is strongly associated with Monroe's two-term presidency,  from 1817 to 1825.   President Monroe made goodwill tours of the country in 1817 and 1819 to promote national pride and national unity.

explanation: we can only guess at how our actions may be perceived in the future. doing something really big like killing lots of people, saving lots of people, affecting the lives of lots of people is a sure fire way of being remembered in historical records. we can also make a difference in the history records by being a small influence on something bigger, whether that is as a civil servant, scientist or artist.

of course you could argue that we all affect history just as tiny cogs in a   bigger machine.

if you mean how do people influence our opinions of things which have already happened, then simply by writing a book which looks at things form a different perspective and trying to convince people that this perspective is more accurate or truthful. people do it all the time i.e. richard the third was a terrible or was he? plenty would disagree, it's just that their views aren't the most widely known.n:

you aint got nothin on my lil weenies