A new milestone has been reached in the United States:  For the first time, more than half of all American adults live in households with cellphones but no landline telephones.

That’s the key takeaway finding from a recent survey of ~24,000 Americans age 18 and above conducted by market research firm GfK MRI.

This finding  mean that in just six years, the percentage of adults living in cellphone-only households has doubled. In GfK’s 2010 research, the percentage was just 26%.

Not surprisingly, there are significant differences in the findings based on age demographics:

• Millennials (born 1977 to 1994): ~71% live in cellphone-only households
• Generation X (born 1965 to 1976): ~55%
• Boomers (born 1946 to 1964): ~40%
• Seniors (born before 1946): ~23%

Interestingly, despite their relatively low adoption rate, the percentage of Seniors living in cellphone-only households actually quadrupled over the past six years.

As for an ethnic breakdown, Hispanic Americans are significantly more likely to live free of landline phones compared to the other three major groups:

• Hispanic Americans: ~67% live in cellphone-only households
• Asian Americans: ~54%
• Whites: ~51%
• African Americans: ~50%

Perhaps surprisingly, the Northeast region of the United States has the lower incidence of cellphone-only households (~39%), compared rates all over 50% in the other three regions. As it turns out, the Northeast has relatively higher levels bundled communication services (TV, Internet, landline and cellphone services), but one suspects that the figures will come into alignment in the next few years and many of those bundled programs bite the dust.

At this rate of change, could we be seeing effectively the end of landline phone service within the next two decades? It seems likely so.

How about you?  Have your cut the phone cord yet?  And did you regret it for even one minute?