Covered Bridge

This bridge is one of the longest of four Howe truss bridges left in Pennsylvania. William Howe patented his design in 1840, His was the first to use iron with wood and was the forerunner of all-iron bridges. Most of the railroad bridges built in the late 1800s used Howe trusses. . Howe's design allowed builders to use green wood; they could adjust the iron rods with turnbuckles as the wood seasoned or shrank. Builders returned to the bridge a year after building to tune- up the spans. . Howe'. design made factory production possible. A foundry in New England produced iron rods, nuts, and Howe's patent angle blocks. Almost any good wood could be used.

"We saw some men today, mending the roads-I did not think a Pennsylvanian ever touched a road or made a bridge, for we are obliged to ride thro' every stream we come to-"

Margaret VanHorn Dwight, 1810

Pennsylvania's pioneers urgently needed bridges. High water made even the smallest streams risky crossings. Bridges, and ways to build them, evolved rapidly. Bridge-builders used the cheapest and most abundant material-wood. . Why cover a wooden bridge? The answer is to protect the bridge's sup- porting structure-its sides or trusses- from rot. It works; this bridge has been standing since 1874.

How Trusses Evolved

The first wooden bridges were two stringers aid across a creek. However, they could only be as long as the trees were tall and couldn't support much weight.

Next, builders added a triangle to support the stringers. This bridge often washed out in ice and high water.

Finally, builders discovered that the triangle supported the bridge, whether en top or on bottom. All bridges use triangles in one form or another to support the bridge's weight and any load on it.

Bridge Tolls

Most bridges were privately built to make money for their owners. Governments were not yet in the bridge-building business. Some millers built bridges to provide access to their mills. . Bridge owners gave doctors, clergy and large families discount rates. For church- goers on Sundays, toll-takers waived tolls and left shoe cloths at either end so people could wipe dust from their shoes. Mill-owned bridges didn't charge tolls for those hauling grain to the mill. . Charge accounts were common since many people carried no money. Farmers kept tallies scratched on their wagon seats. . Life in a Bridge

Little-used bridges were shelters for town meetings, church services, and rallies. All bridges were used for advertising. . Rafters were great for acrobatic youngsters. They also occasionally harbored robbers. . Most covered bridges were known as kissing or wishing bridges. Sweethearts kissed while hidden in the darkness. If you make a wish as you go through, it should come true. . This historical marker is in McConnell's Mill in Lawrence County Pennsylvania