Twenty-one years ago, Cal Ripken Jr. played in his 2,131st consecutive game, breaking the record previously set by Lou Gehrig. Ripken’s streak didn’t end for another 501 games.

In honor of that milestone — and his record that won’t be broken anytime soon — we look at the sports marks that are least likely to fall, and which active athletes are closest to breaking them:

Cal Ripken Jr.’s 2,632 consecutive games played

Active leader: Alcides Escobar, 146 games

The Major League Baseball season is 162 games, which means Ripken played over 16 seasons without missing a beat. If Escobar wants to rewrite history, he’ll have to play in every game until he’s 45 years old. That’s 16 more years.

Barry Sanders’ five 1,500-yard seasons

Active leader: Adrian Peterson, 2 seasons

Sanders holds the NFL record for most seasons with 1,500 or more rushing yards. Peterson, 31, has had two such seasons, and he has already played in the NFL for nine years. To catch up to Sanders, Peterson will have to be in tiptop shape for the next three seasons. He just missed the mark last season, rushing for 1,485 yards.

Wayne Gretzky’s 2,857 career points

Active leader: Jaromir Jagr, 1,868 career points

When he retired in 1999, the Great One held more than 60 NHL career records and many of them won’t be broken anytime soon, if ever. No player since 1996 has reached 140 points in one season. A player could put up 140 for 20 straight seasons and still not reach Gretzky.

Joe DiMaggio’s 56-game hit streak

Active leader: Ender Inciarte, 14-game streak

DiMaggio’s streak began on May 15, 1941, and ended July 17 of that year. During his streak, Joltin’ Joe was 91-for-223 (.408) with 15 home runs and 55 RBIs. To top DiMaggio, Inciarte needs a hit in his next 43 games.

Brett Favre’s 321 consecutive starts

Active leader: Eli Manning, 194 consecutive starts

Favre not only holds the record for most consecutive starts but also for most passing yards, most pass completions and most starts, among others. Manning can make Favre’s durability record fall, but he can’t miss a start for the next eight seasons. Manning is already 35 years old.

Jerry Rice’s 1,549 career receptions

Active leader: Andre Johnson, 1,053 receptions

Rice is arguably the greatest wide receiver to ever play the game. He spent 20 years in the NFL with the San Francisco 49ers, Oakland Raiders and Seattle Seahawks. If Johnson averages 80 receptions per season — he averages 81 currently — for the next six seasons, Rice’s record will fall. But what are the chances the 35-year-old has six more seasons?

Emmitt Smith’s 18,355 rushing yards

Active leader: Frank Gore, 12,040

Smith accumulated a ridiculous number of rushing yards with the Dallas Cowboys and Arizona Cardinals during his 15 seasons in the league. In order for Gore, who is in his 13th season, to break his record, he would have to have an average of 4.2 yards per carry on the next 1,504 carries. Based on his career averages, that would take him 92 games or about six seasons.

UCLA men’s basketball team’s 88-game winning streak

Active leader: Villanova Wildcats, 6 games

John Wooden and UCLA started the 1970-71 season on a winning streak and didn’t lose a game until Jan. 19, 1974. Nova will have to string together at least two perfect seasons in a row to get there. There has not been a perfect season in college basketball in 39 years.

Connecticut women’s basketball team’s 90-game winning streak

Active leader: UConn Huskies, 75 games

UConn has been a juggernaut in Division I women’s basketball for some time. The Huskies didn’t lose a game from the start of the 2008-09 season until Dec. 30, 2010. And now, fresh off their fourth straight national title, they are attempting to break their own record. They’re getting pretty close.

Cy Young’s 511 career wins

Active leader: Bartolo Colon, 231 career wins

Young pitched for five different teams throughout his 21-year career. He has held his record for over a century and has more than twice as many wins as the closest active pitcher. Colon is already 43 years old and averages 13 wins per season. At that rate, it would take him around 21 seasons to come anywhere close to Young. He would be 64 by then so, yeah, it doesn’t seem probable.