Ever since Jefferson penned the Declaration of Independence, we celebrate with a day of relaxation, barbecues, and the pageantry of dazzling fireworks. Little known is that in 1776, Jefferson had a second great vision that shaped the United States. Like the Declaration, his second vision also relied on citizens relishing civic duty and claiming their right to be informed and educated in order to self-govern and curb corruption, privilege, and aristocracy. The Jeffersonian plan was to provide a thermometer to a deputy in every county in Virginia with instructions to log twice-daily observations of temperature and wind direction. This founding father envisioned what is nowadays called citizen science.

In the legacy of this tradition, in every state of the union, hundreds of thousands of people will be scientifically engaged this summer: observing, measuring, analyzing, checking. Don’t be alarmed if your seemingly ordinary neighbors chronicle the sequence of flower blooms, measure gravestones, or count the pulsing of fireflies. Sharing observations is a collective scientific effort. Across all age levels and segments of society, citizen science is undergoing a revival as an American leisure-time tradition that was born with our Independence.

The Revolutionary War temporarily held up Jefferson’s systematic statewide plan. But from 1776 to 1816, which includes his two terms as President, Jefferson and many of his recruits (including Lewis and Clark) kept a near complete series of weather observations. Those founding our independent nation had a friendly rivalry with Europeans about who lived on the better continent. But, as relative newcomers to the New World, they had little data to support their claims of superiority. It was Jefferson’s patriotic chip on his shoulder, in a time before meteorologists and climatologists, which caused him to enlist citizens in data collection. In particular, weather records were a key part of his efforts to dash the theory of degeneracy: the idea that the temperature and humidity of New World produced animals that were smaller, weaker, and just plain inferior to their European counterparts. Jefferson used weather data, which included his 5 years in France, to show that America had a higher sunny-to-cloudy-day ratio than Europe.

Jefferson’s plan was not formalized until 1870, when President Grant created a new federal agency and assigned it the responsibility to coordinate a volunteer weather observer program. This is today’s National Weather Service’s Cooperative Weather Observer Network which draws about one million volunteer-hours annually at 12,000 sites across all 50 states.

When poor weather forecasting led to disaster in the foothills of the Rockies in 1998, Jefferson’s tradition expanded again with the formation of the Community Collaborative Rain Snow & Hail Network (CoCoRaSH). Radar (Radio Detection and Ranging) can estimate rainfall over large areas, but precipitation is highly localized. It can rain, snow, or hail on one side of the street and not the other. Nothing high-tech in the sky can beat a gauge on the ground. Now meteorologists, claims adjusters, attorneys, construction businesses, utility companies, mosquito control experts, farmers, and urban planners use the publicly accessible, fine-scale data from CoCoRaSH.

In the 21st Century, Jefferson’s legacy intersected with the Internet and mobile phones. The result has been a proliferation far beyond what he ever conceived. Instead of hopping a stagecoach to share observations with friends, with a few keystrokes observations are shared globally and archived in perpetuity. Citizen science is now a global hobby, connecting people and their real-world leisure observations to virtual databases.

People count butterflies in abandoned fields, tally washed-up garbage on beaches, record bird species at backyard feeders, and spend hours sitting at their computers classifying galaxy after galaxy (there are hundreds of thousands of them). Stalwart science militia called Invaders of Texas scour the countryside, eyes peeled for possible invasive species that may threaten the environment or economy, be they plant, bird, or mollusk. In London, the Bronx, and San Francisco, people use smartphone apps to document noise pollution, then direct local changes in truck traffic routes. North of the Arctic Circle, Inuit measure ice thickness. In the Himalayan high peaks, Nepalese villagers record snow leopard sightings and tracks.

Scientific knowledge is now widely co-produced through collaborations between scientists and society. Citizen science, with millions of hours of volunteer work, can stretch tight budgets, and collectively reveal large-scale patterns that scientists could never discover alone.

Citizen science gives people an unselfish, guilt-free reason to take a break, go outside, and slow down enough to observe their world. In return they gain discoveries, large and small, that they never forget. These activities may alter their lives and shape how participants view themselves, their environments and communities.

Science-as-hobby builds social capital, the properties of trust, norms, and personal connections that enable communities to thrive.

Without public participation, science can appear as a quagmire of jargon and uncertainty. With public participation, science encourages people to retain the child’s pleasure of wonder and enchantment in understanding our world. Another reason that Jefferson wanted weather data was to develop a theory of climate, but his inspiration for it was a deep-seated love of the seasons. On weather collection, Jefferson wrote “Climate is one of the sources of the greatest sensual enjoyment.”

Co-producing knowledge can bring political agency. Hobbyists who engage in science have the ability to enter public discourse, with their opinions and their data, when it really matters: when too many of our kids have asthma, when our quality of water is at risk, and when we want a future with sustainable energy.

This Fourth of July, make your leisure matter. Discover a ladybug, tag whale songs online, or monitor a local stream. Collaborate and feel a newfound capacity to influence decisions. Independence means we don’t leave governing solely to career politicians; likewise, we shouldn’t leave knowledge production solely in the hands of professional scientists. We have two intertwined legacies to protect—democracy and citizen science. Celebrate Jefferson’s other enduring vision: become a citizen scientist.