Modern Valentine's Day has been strongly influenced by American traditions that first derived from the mid-19th century. Esther A. Howland in the 1840s began selling cards and gifts that contained real lace, ribbons and colorful pictures. It was also this time that women began to be more strongly associated with Valentine's Day relative to men, where marketing began to focus more on them and today they constitute about 85% of Valentine's Day sales. It was around 1900 that Valentine cards were popularly produced throughout Europe and began to replace letters and notes that lovers would exchange. Valentine cards often contained secret compartments that the women of affection would have to find, which may have contained additional messages .