- Jul 1 At least 626 ships lie at anchor around San Francisco Bay
- Jul 2 Benjamin Lane patents gas mask with a breathing apparatus
- Jul 7 Scottish explorer Edward Eyre reaches Albany, Western Australia
Historic Event
Jul 10 Millard Fillmore sworn in as President of US (replacing Taylor)
- Jul 12 Dutch 2nd Chamber accepts establishment of Provincial States
- Jul 14 1st public demonstration of ice made by refrigeration by Florida physician John Gorrie
- Jul 15 John Wisden bowls all 10 South batsmen, North v South at Lord's
- Jul 17 Harvard Observatory takes 1st photograph of a star (Vega)
- Jul 19 Airship Elizabeth leaves in storm for Fire Island, crashes (42 die)
- Jul 23 17th Postmaster General: Nathan K. Hall of NY takes office
- Jul 25 Gold discovered in Oregon (Rogue River)