original US political parties: Federalists/well-to-do socio-economic types, strongest proponents of 1787 constitution, initially led by Alexander Hamilton who favored strong central government ruled by wealthy/educated who would encourage development of commerce/manufacture, party name was public relations gambit in attempt to convey continuity as government under first constitution, Articles of Confederation, was considered 'federal' in that it was state, not national, based (see James Madison, *Federalist #39 for explantion of government established by 1787 constitution as neither national nor federal as terms were used in those days)
Democratic-Republicans/'middle' strata 'common man' types, initially led by Thomas Jefferson (supporters are sometimes called Jeffersonian Republicans) and, to lesser extent, James Madison, favored less expansive national government (at least until Thomas Jefferson became president), was initially called Republican Party to convey opposition to both aristocratic government and direct democracy and support for republican government which commonly meant elected representatives in early US, rhetoric portrayed Federalists as 'royalists' and, in return, Federalists called Jefferson's party 'Democratic-Republican' in effort to link it to French radicals (label stuck)
for all practical purposes, D-R Party was only party between mid-1810s and mid-1820s (although Madison had given Federalists a bit of life with unpopular War of 1812 against Britain)
D-R Party split in 1820s: Democrats/associated with Andrew Jackson, new states were being admitted and they generally did not require white males to own property in order to vote, party name was attempt to win support of expanded electoral in so-called 'era of the common man', generally identified with state-rights positions
Whigs/originally called National Republicans, formed by John Quincy Adams (John Adams' nephew who defeated Jackson for US president in 1824), Henry Clay, and Daniel Webster to oppose 'Jacksonian democracy' and promote strong national government, coalition of bankers, businesspersons, and some southern planters (same types that had supported Federalists), adopted Whig name reflected socio-economic similarites to British party of same name
by early 1850s, Whigs were so weak that anti-slavery activists and those who opposed allowing slavery to expand into western states and territories gained control of party effectively driving southern planters out of party
Republicans/formed amidst breakup of Whig coalition, while anti- slavery activists (including some Democrats) fueled party, some members wanted no expansion of slavery, party also favored land grants to railroads, new banking system, protective tariffs, and homestead law to provide cheap western farming lands, party name conveyed attempt to link it to Jefferson's party that was originally called Republican Party
so names of two major contemporary US parties have been around since late 1820s (Dems) and mid-1850s (Reps) although the parties have experienced changes over time (such as blacks - when not disenfranchised - voting Republican from after Civil War until 1930s New Deal to blacks being the most solid Democratic voting bloc since 1960s and Democrats controlling south for a century after Civil War until their passage of civil rights legislation in 1960s began to erode southern support) Michael Hoover