The founder of Meetup.com has said he was inspired by the book Bowling Alone, by Harvard sociologist Robert Putnam, about the decline of community in America. "People were staying in front of their computers, DVD players and TVs more and more, and losing personal connections," and Meetup wanted to "do something positive in the world by having people reconnect—not with people in chatrooms across the globe—but in their own communities." We know of Meetup mostly as a political organizing tool. But there are thousands of people in the DC area who use it just to meet folks who want to do things together -- including going hiking.
The MD.DC.VA Hiking Group is another extremely active Meetup with over 2,000 members and multiple activities every week, regularly getting a dozen or more people for each event on the weekends. Hikes are rated for pace and/or difficulty, so you can find one that meets your desires and abilities.
Outdoors for Beginners is a group with over 2,000 members aimed at folks without much outdoors experience. "But this is not an outdoors-for-dummies group," they say. "We try to keep it challenging, but without making it impossible. We make sure it will be fun, not intimidating...On our own we could learn to hike, to ski, or snorkel, but how much fun is that? It is always better when we do it together."
The Nature Lovers Meetup has about 1,300 members and has held nearly 150 events over the last two and a half years, and they can get turnout from 5 to 30 people. Events include hiking, camping, volunteer activities, and even some book discussions. "Meet other outdoors enthusiasts who are environmentally conscious and spiritually inclined," they say.
Young Adventurers and Company is a meetup aimed at the under-40 crowd who "love the thrill of the outdoors." They regularly have a dozen or more participants at their events, and activities have included skiing, tubing, and other adventures as well as plain old hiking.
Wandering Soles is a group organized by the head of the Sierra Club Potomac Regional Outings, and their events are often cross-listed. They don't require RSVPs, but they still show at least a dozen people saying they're coming to many events. Events are primarily day hikes and have ratings from easy to difficult.
Mid-Atlantic Backpackers and the Fairfax Camping Group are organized specifically for folks who want to go on overnight trips. Mid-Atlantic Backpackers trips are mostly in the mountains and as far away as Tennessee; the Fairfax group stays a little closer to home.
The Northern VA Walking Group takes easy-to-moderate, dog- and kid-friendly walks in places like Huntley Meadows, Manassas Battlefield, Arlington Cemetery, and the C&O Canal, as well as some that are farther away. They've got about 470 members, and get a nice-sized turnout of 7 to 15 people for many of their walks.
The 20s/30s Hiking/Camping Group just started in September and already has over 120 members. "I started this group to bring together young, fun, outgoing people in the MD/DC/VA area that are active and like to be outdoors," says the organizer.
The Primitive Earth Skills group is a small, brand new group that works together on primitive living/survival skills such as edible wild plants, shelter construction, flint-knapping, basket-weaving, and light-impact camping. The organizer is an instructor at Ancestral Knowledge, but the group is aimed at folks who already have some skills and want to practice them together.
Even newer is the Maryland LGBT Nature Lovers Group. "This group is for nature loving, tree hugging, dirt worshipping lgbt people and anyone who wants to be in the presence of good company doing fun stuff in the outdoors! Lesbian moms, gay dads and all lgbt families & children are welcome to be part of our adventures."
The $3 Charity Hikers are a small, but worthy, group. They collect $3 from each hiker, to be donated to charity.
You can join any of these groups and get email reminders about their events. In general, we don't add Meetup hikes to our own calendar of nature events in the DC area -- there are just too many, and they get updated too frequently.