The finalized copy of the United States Declaration of Independence was signed by congress.
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Musical.ly and TikTok merged, combining the users of both apps to form one community.
Researchers in South Korea developed a tattoo that monitors a person's health.
Andrew Hallidie introduced the cable car to San Francisco after witnessing a horse and carriage accident.
Samuel Briggs and his son patented his nail-making machine.
The Tower Subway in London became the first underground tube railway to open.