House Minority Whip Steny Hoyer (D-Md.) was an early adopter among House leadership, joining in July. He has since shared 47 photos, many using the filters that have helped make Instagram so popular with cellphone camera users.

President Obama and Mitt Romney both used Instagram for their campaigns.

And House Republican Whip Rep. Kevin McCarthy (R-Calif.) and House SpeakerBoehnerJohn BoehnerMarch is the biggest month for GOP in a decade House markup of ObamaCare repeal bill up in the air Conservatives to Congress: Get moving MORE" href=""> John BoehnerJohn BoehnerMarch is the biggest month for GOP in a decade House markup of ObamaCare repeal bill up in the air Conservatives to Congress: Get moving MORE (R-Ohio) signed up this month, following a long list of other members who began using the service this year, including Rep. Paul RyanPaul RyanDem leaders try ‘prebuttal’ on Trump Ryan, McConnell predict ‘positive, upbeat’ message from Trump Retired generals urge Congress not to cut funds for diplomacy MORE (R-Wis.), Sen. John McCainJohn McCainTrump fires opening salvo in budget wars Overnight Finance: Trump budget to boost military, slash nondefense spending | Senate confirms Commerce pick | House Intel chief won't subpoena tax returns Overnight Defense: Trump proposes 3B defense budget | Defense hawks say proposal falls short | Pentagon to probe Yemen raid MORE (R-Ariz.) — who was introduced to Instagram by his daughter, Meghan, in April — Rep. Debbie Wasserman Schultz (D-Fla.), and others.

Instagram, usually accessed by mobile app, now has more active daily visitors on mobile than Twitter does, according to a comScore report in September. An average of 7.3 million smartphone users accessed Instagram every day in August, compared to 6.9 million daily visitors using Twitter on mobile that month. Lawmakers are starting to join that trend, likely an acknowledgement that an increasing number of Americans — 27 percent during the 2012 campaign, according to a Pew Research study — are using their cellphones to stay up to date on politics.

“There are a lot of people interested in photos and photography and this is a great way to share that,” a McCarthy digital aide said. “Like a lot of other social mediums that members are using today, [Instagram is] about connecting with the American people. It’s about creating open dialogue with them.”

McCarthy, like many other members of Congress, also shares photos on his Facebook and Flickr pages, but the aide said Instagram photos are specifically curated for the Instagram audience.  

So far, members of Congress have used Instagram to share snapshots of interesting meetings — such as Boehner showing Myanmar's opposition leader Daw Aung San Suu Kyi the view from his balcony — and scenes around Capitol Hill — such as the arrival of the Capitol Christmas Tree and the statue of Thomas Jefferson in the Capitol rotunda. McCarthy’s aide said they also plan to share photos from the congressman’s California district.

Members of Congress are also beginning to use Instagram to connect with one another. McCarthy and Rep. Scott DesJarlais (R-Tenn.), who joined the service on Thursday, quickly found one another on Instagram this week.