In all U.S. history, only six minor parties have ever polled as much as 1% of the presidential vote at least twice, and two of those six parties exist today. This statement only applies to parties that had their own presidential nominee, and which didn’t nominate the presidential nominee of some other party.
The six parties, the years they polled at least 1% for president, and their percentages, are:
Free Soil: 1848 10.13%; 1852 4.94%
Greenback: 1880 3.35%; 1884 1.74%
Prohibition: 1884 1.50%; 1888 2.20%; 1892 2.25%; 1900 1.50%; 1904 1.92%; 1908 1.70%; 1912 1.39%; 1916 1.19%
Socialist: 1904 2.98%; 1908 2.83%; 1912 5.99%; 1916 3.16%; 1920 3.43%; 1932 2.23%
Libertarian: 1980 1.06%; 2016 3.29%
Green: 2000 2.74%; 2016 1.02%
The percentages for the Libertarian and Green Parties in 2016 might change slightly before all the votes are counted. They won’t change very much and they are more likely to increase than to decrease.
The four older parties mentioned above were able to see large part of their platforms enacted into policy. This is especially true for the Free Soil, Greenback, and Prohibition Parties, but not quite so true for the Socialist Party.