Drams and Gills

This diagram from the Columbia Gorge Discovery Center and Museum in The Dalles, Oregon, shows the comparisons between drams, ounces and gallons.

It’s often mentioned in the Lewis and Clark journals that whiskey was rationed out by the gill or dram. Joseph Whitehouse wrote on June 9, 1805, “…the officers gave the party a dram, the fiddle played and they danced late &c…”

How much was a gill? The Oxford English Dictionary defines a gill as "a measure of liquids containing one fourth of a standard pint." Thus, at one-fourth of a pint, a gill equates to four ounces. With two pints to the quart and four quarts to the gallon, there are 32 gills to the gallon.
A fluid dram equals one-eighth of a fluid ounce (the equivalent to two average-size thimbles), so there would be 128 drams per pint and 1,024 drams per gallon. So, there are 32 drams in a gill.

Lewis and Clark NHT Visitor Centers and Museums

This map shows a range of features associated with the Lewis and Clark National Historic Trail, which commemorates the 1803-1806 Lewis and Clark Expedition. The trail spans a large portion of the North American continent, from the Ohio River in Pittsburgh, Pennsylvania, to the mouth of the Columbia River in Oregon. The trail is comprised of the historic route of the Lewis and Clark Expedition, an auto tour route, high potential historic sites (shown in black), visitor centers (shown in orange), and pivotal places (shown in green). These features can be selected on the map to reveal additional information. Also shown is a base map displaying state boundaries, cities, rivers, and highways. The map conveys how a significant area of the North American continent was traversed by the Lewis and Clark Expedition and indicates the many places where visitors can learn about their journey and experience the landscape through which they traveled.