Oct. 07, 2016, 1:29 p.m. (ET)

Team USA athletes were wildly successful at the Rio 2016 Olympic and Paralympic Games, which meant one thing: lots and lots of smiles! In honor of World Smile Day, check out 16 of Team USA's biggest grins.

1) The Final Five
(L-R) Simone Biles, Gabby Douglas, Laurie Hernandez, Madison Kocian and Aly Raisman stand on the podium for the national anthem at the medal ceremony for the women’s gymnastics team final at the Rio 2016 Olympic Games at the Rio Olympic Arena on Aug. 9, 2016 in Rio de Janeiro.

2) Michael Phelps
Michael Phelps poses on the podium during the medal ceremony for the men's 200-meter butterfly at the Rio 2016 Olympic Games at the Olympic Aquatics Stadium on Aug. 9, 2016 in Rio de Janeiro.

3) Kristi Castlin, Brianna Rollins and Nia Ali
(L-R) Kristi Castlin, Brianna Rollins and Nia Ali celebrate with American flags after the women's 100-meter hurdles final at the Rio 2016 Olympic Games at the Olympic Stadium on Aug. 17, 2016 in Rio de Janeiro.

4) Kerri Walsh Jennings and April Ross
Kerri Walsh Jennings (L) and April Ross pose on the podium during the medal ceremony for women's beach volleyball at the Rio 2016 Olympic Games at the Beach Volleyball Arena on Aug. 17, 2016 in Rio de Janeiro.

5) Women's Volleyball Team
(L-R) Christa Dietzen, Courtney Thompson, Jordan Larson-Burbach and Foluke Akinradewo celebrate after winning bronze in women's volleyball at the Rio 2016 Olympic Games at the Maracanazinho on Aug. 20, 2016 in Rio de Janeiro.

6) Gwen Jorgensen
Gwen Jorgensen celebrates as she wins gold in women’s triathlon at the Rio 2016 Olympic Games at Fort Copacabana on Aug. 20, 2016 in Rio de Janeiro.

7) Allyson Felix
Allyson Felix reacts after winning gold in the women's 4x400-meter at the Rio 2016 Olympic Games at the Olympic Stadium on Aug. 20, 2016 in Rio de Janeiro.

8) Carmelo Anthony
Carmelo Anthony celebrates after defeating Serbia for the men's basketball gold medal at the Rio 2016 Olympic Games at Carioca Arena 1 on Aug. 21, 2016 in Rio de Janeiro.

9) Megan Fisher
Megan Fisher celebrates on the podium at the medal ceremony for the women’s track cycling C4 3,000-meter individual pursuit at the Rio 2016 Paralympic Games at the Olympic Velodrome on Sept. 8, 2016 in Rio de Janeiro.

10) Hailey Danisewicz, Allysa Seely and Melissa Stockwell
(L to R) Hailey Danisewicz, Allysa Seely and Melissa Stockwell celebrate on the podium at the medal ceremony for the women’s paratriathlon PT2 at Forte de Copacabana at the Rio 2016 Paralympic Games on Sept. 11, 2016 in Rio de Janeiro.

11) David Brown and Jerome Avery
David Brown (L) and guide Jerome Avery celebrate on the podium at the medal ceremony for the men’s 100-meter T11 at the Rio 2016 Paralympic Games at the Olympic Stadium on Sept. 11, 2016 in Rio de Janeiro.

12) Cortney Jordan and McKenzie Coan
Cortney Jordan (L) and McKenzie Coan celebrate on the podium at the medal ceremony for the women’s 400-meter freestyle S7 at the Rio 2016 Paralympic Games at the Olympic Aquatics Stadium on Sept. 14, 2016 in Rio de Janeiro.

13) Alana Nichols
Alana Nichols celebrates after finishing the women’s paracanoe KL2 final at the Rio 2016 Paralympic Games on Sept. 15, 2016 in Rio de Janeiro.

14) Chelsea McClammer, Tatyana McFadden and Amanda McGrory
(L-R) Chelsea McClammer, Tatyana McFadden and Amanda McGrory celebrate their podium sweep in the women's 5,000-meter T54 at the Rio 2016 Paralympic Games at the Olympic Stadium on Sept. 15, 2016 in Rio de Janeiro.

15) Natalie Schneider
Natalie Schneider celebrates with the American flag after winning the gold medal in women’s wheelchair basketball at the Rio 2016 Paralympic Games on Sept. 16, 2016 in Rio de Janeiro.

16) Nicky Nieves
Nicky Nieves celebrates during the women’s sitting volleyball final against China at the Rio 2016 Paralympic Games on Sept. 17, 2016 in Rio de Janeiro.