Why were all white men given the right to vote in the new territories?

To get settlers in the territory is the right answer.

Explanation:

In order to get more immigrants, the administration used its one of the most powerful tactics of manhood suffrage. The government granted suffrage to all white men either they had land or not. Apart from this, the administration also set up the prices of the land at very low so that the settlers could easily buy large tracts of land at low prices. Hence, to encourage people to move and settle, the administration even awarded voting rights to those who had no land.

social contract theory, nearly as old as philosophy itself, is the view that persons' moral and/or political obligations are dependent upon a contract or agreement among them to form the society in which they liv

b. young children below the minimum age were working