Why is the the Red Line called “the Red Line?” And how many trains does the MBTA have?

Riders will have these questions and many others answered during their commutes as the MBTA rolls out a new campaign that celebrates the 115th birthday of America’s oldest subway system.

“Fun fact” inserts will be placed inside different train cars, coaches and buses along the MBTA’s lines as part of their “CuriosiTy” initiative, which offer travelers little-known information about the T, like how subways and streetcars travel 85,736 miles every day.

“That’s enough to travel around the world 3 times,” according to one of the placards that will be placed inside the vehicles.

The cards will begin to appear this week, according to officials.

“Public transit in Boston has a rich history,” said MassDOT Secretary and CEO Rich Davey in a statement Monday.  “We try hard to keep our customers up to date with the latest technology like mobile apps, mobile ticketing and our new countdown clocks; this CuriosiTy Campaign is a fun way to remind our customers that we’ve always had this innovative spirit.”

All the CuriosiTy facts were researched by Christopher Lynch, a member of the MassDOT Performance Management and Innovation Team, according to T officials.

“Our customers are very engaged and knowledgeable about our present services,” said MBTA Acting General Manager Jon Davis. “We hope transporting them back in time to the start of service in 1897 and some big milestones in between will brighten their trip.”

The cards put the icing on the cake as the T celebrated it’s more-than-a-century-old system by opening a Charlie Card store in Downtown Crossing and unveiled the life-like MBTA mascot “Charlie” at the beginning of the month.

Below are samples of the cards that will be going up this week and give you something to think about while you travel on the T.