It took 60 years as the westward expansion took place from 1801-1861.
The answer is bicameral legislature.
<em>A bicameral legislature</em> means the legislature consists of two separate legislative chambers (houses). Only Nebraska has a unicameral system, with one chamber only (Nebraska does not have the lower house but the legislators are called senators for historical reason). The unicameral legislature in Nebraska is called Nebraska Legislature.
The smaller chamber is usually called <em>Senate,</em> in 41 states the larger chamber is called <em>House of Representatives</em>, in five Assembly and in three House of Delegates. The smaller chamber usually confirms appointments made by the governor, the larger one initiates taxing legislation.
I think it is the second one
