Simplify the following text for a Grade 7 native English-speaking person.
Original: The discovery of silver at the Comstock Lode in 1859 led to a population boom that was an impetus to the creation of Nevada Territory out of western Utah Territory in 1861 .
Simplified: The eastern part of Nevada was part of `` Utah Territory '' and the southern part was part of `` New Mexico '' . In 1859 in the Comstock Lode , gold and silver were first discovered .