Here’s a travel trend we can get behind: Travel in support of independent booksellers. Larry Portzline started the venture last year as a “grassroots campaign to promote and support independent bookstores by marketing them as a travel and tourist destination.” “It all started last July, when Portzline organized another group of 45 book lovers to travel from Harrisburg to Manhattan to visit 18 bookstores in Greenwich Village,” writes Jane Van Ingen in Poets and Writers magazine. “During the four-hour bus ride to the city, Portzline gave a presentation about competition in the bookselling industry. During the day, travelers visited landmark bookstores such as the Strand and Three Lives and Co., as well as niche stores that sell only cookbooks, foreign-language titles, children’s books, or mysteries.” Next trip: A June 12 excursion, also from Harrisburg, where Portzline works at the local community college, to New York City.  Through his Web site, Portzline encourages others to coordinate trips in their own areas. “Wouldn’t it be great,” he writes, “to see busloads of book-lovers pulling up in front of independent bookstores on a regular basis?”