What are some examples of "electoral tie" in the history of the USA and how they were resolved? Were some presidents elected by the Congress? Was there ever free voting in the electoral college?
It has happened exactly twice where Congress had to decide the results of the presidential election. The 1800 election resulted in a tie between a potential president and vice presidential candidate. At the time, each elector voted twice, the person with the most votes won, the person with the second most votes became VP, so long as the first had at least half of the EC votes. This was the first year of political parties, with a presidential candidate running with a vice presidential candidate. They each received the same number of votes, leading to much confusion.
The second situation happened in 1824. 4 candidates received EC votes. In the end, it was not the person with the most original EC votes that became president (Andrew Jackson), but rather the person with the second most (John Quincy Adams). This was very controversial in the day, and the same election between the two resulted in Andrew Jackson winning the 1828 election.
1824 is the best example. This tie was not a traditional tie, it is the type of "tie" that happened in the regular Senate election in Georgia in 2020: there was one candidate who won a plurality of both popular and electoral votes, and another candidate was selected. The problem was that the plurality was not also a majority.