The distance upgrade is an upgrade you can buy at Steve's General Store. Like the name implies, each time you buy it the range for your pickaxe increases. Therefore, you could grab some ores that are slightly out of reach. It also helps a lot if you like strip mining. It could decrease the amount of blocks you have to walk to reach the next.
The cost of an upgrade multiplies by about 1.6x each time you buy the previous one. There are 12 upgrades in total.
|Upgrade Number||Cost ($)|