What major discovery in the U.S. produced over $340 million in gold and silver by 1890 and allowed Nevada to join the Union?

The correct answer is the Comstock Lode, which was a significant silver discovery in Nevada that began in 1859. This major mining discovery led to the extraction of substantial amounts of silver and some gold, generating over $340 million in revenue by 1890. The immense wealth generated from the Comstock Lode significantly impacted Nevada's economy, population growth, and overall development, ultimately contributing to its admission into the Union as the 36th state in 1864.

The Comstock Lode's discovery was crucial for several reasons. It attracted a large influx of miners and settlers to the area, which increased the population necessary for statehood. This rush not only contributed to Nevada’s economy but also played a role in the broader context of westward expansion during the period. As a result, Nevada's significant mineral wealth and rapid population growth made it a prime candidate for statehood in a relatively short amount of time.

In contrast, the other choices refer to different historical contexts. The Oklahoma Territory pertains to the era of land rushes and the settlement of the Great Plains, the Chinese Exclusion Act relates to immigration policy, and the Homestead Act was a piece of legislation aimed at facilitating westward expansion by granting land to settlers. None