The Democrats do not chose the President; the American people do. Electors of the Democratic party choose their candidate at their annual National Convention, which has no specific date.
He is officially "sworn-in" as the next President.
No president officially changed it, some loser in the streets decided Veteran's day was cool name and changed it. Then it spread and soon losers all over the world were calling it Veterans day!
The Presidential Inauguration Day is held on January 20. The term of the president officially starts at noon on that day.
The president officially assumes his position as U.S. president on inauguration day. The inauguration ceremony is usually held on January 20th.
Armistice Day was officially renamed to Memorial Day by legislation signed by President Lyndon B. Johnson in 1967.
Presidents' Day (officially known as "Washington's Birthday", but also known as "President's Day" and "Presidents Day") commemorates the accomplishments of the various Presidents of the United States.It mostly honors presidents George Washington and Abraham Lincoln.
Woodrow Wilson
You may be referring to the oath of office. But the electoral college is what officially elects the president. A presidential candidate may win the popular vote, but without enough electoral votes, he (or one day, she) will not be officially elected.
In May of 1967 President Lyndon Baines Johnson signed the legislation officially renaming Decoration Day to Memorial Day. But the name Memorial Day had been commonly used since after World War I.
The electors are chosen by popular vote in every State and on the same day everywhere.
On Inauguration Day, January 20th, 2009. See related links.
That's Inauguration Day, when the winner of the election officially takes office.