After the first event in 1829, the Boat Race was next held in 1836 when the course was from Westminster Bridge to Putney Bridge. The same course was used for the next few races, the last being in 1842. The next race was in 1845, when the course was from Putney to Mortlake. The race has been held on the same course every year since then, except during the two world wars and the COVID–19 pandemic. In 2021, the second year of the pandemic, it was held on the Great Ouse near Ely, Cambridgeshire.
Note: records of the early years may be sketchy, and Wikipedia is not consistent in its various pages. In particular, it's not clear on how many occasions between 1836 and 1842 (when the course was from Westminster to Putney) the race was actually held.
© Haydn Thompson 2022