About 14,000 covered bridges have been built in the United States, mostly in the years 1825 to 1875. The first documented was the "Permanent Bridge", completed in 1805 to span the Schuylkill River in Philadelphia. However, most other early examples of covered bridges don't appear until the 1820s. Extant bridges from that decade include New York's Hyde Hall Bridge and Pennsylvania's Hassenplug Bridge, both built in 1825, and the Haverhill–Bath Covered Bridge and the Roberts Covered Bridge, in New Hampshire and Ohio respectively, both built in 1829.