Chelsea

Chelsea is not at all a traditionally Polish name and it's totally not in line with Polish phonetics, but last year (2019) 6 girls were given the middle name Chelsea. In January 2020, 55 women in the whole population had Chelsea as their first name, while 75 had it as their middle name.

In 2018, 18 is the most common age for an American (U.S.) Chelsea who is registered female with the Social Security Administration. It is the 355th most common female first name for living U.S. citizens.

Although Chelsea, as a name, was first used much earlier than the 1960s/70s, from what I found out, it started increasing in usage for girls in America in 1968 when actress, comedienne, singer and dancer Chelsea Brown (1947-2017) appeared regularly in the second season of Rowan & Martin's Laugh-In which made her the first African-American regular on that show. After increasing steadily in the 70s, it jumped in popularity in 1982 as a result of the film On Golden Pond, released in December of the previous year, where Jane Fonda played the character Chelsea Thayer Wayne.

My name's Chelsea and it was pretty rare back when I was born in '79. I wasn't all that thrilled when I started seeing it on pens and keyrings! It started getting popular in New Zealand when there was a character called Chelsea in a local TV show called Gloss.