It's been a wild four years during President Barack Obama's first term — filled with sweeping attempts at boosting an economic recovery and reforming the nation's health care system, with memorable detours along the way.

Along the way, White House official photographer Pete Souza has been there to document Obama's every move. Souza was the White House's official photographer from 1983-89 during Ronald Reagan's second term in office. It was during his subsequent time as a Chicago Tribune photographer that he documented the rise of then-Sen. Obama and detailed his accounts in a book published in 2008.

Souza has published a selection of his photos on the White House's official Flickr account since midway through Obama's first year in office. Combining these and a few other memorable moments documented by other photographers, we've compiled the 100 most iconic photos from Obama's first term as he prepares for his second inauguration Monday.

(Note: For some of the photos, Souza has added his thoughts or provided some additional background, which we've put below the photos.)