Movements such as the YMCA, Sunday School, Bible Clubs and other organisations did a lot to change this between 1850 and 1950. The real parachurch groups began around the time of the ending of the Second World War, with Young Life, YfC and others starting up and making a real impact in the 1950s and 60s. There was a shift in the 1970s, however, to church's becoming the primary focus of youth ministry. Today, most parachurch youth organisations see their function as supporting local church youth ministry. If you minister in one of the few churches where the youth ministry is well supported financially, and is seen as a priority in the budgeting process, then count yourself really blessed.
Most churches allocate an absolute pittance to youth ministry.
It may be an interesting exercise to calculate what percentage of total income your church spends on its youth. For churches with youth pastors, this percentage may be higher, as salaries account for a large portion of most church's budgets. Many churches would argue against this, saying that only official church members should be taken into account when doing such a calculation. This is obviously ridiculous. Firstly, most young people are not church members simply because most churches have a minimum age requirement for membership.